Melanomas confined to the lung represent an exceptionally rare and diagnostically challenging entity. Whether these tumors constitute true primary pulmonary melanomas or metastases from occult or completely regressed cutaneous primaries remains controversial. We retrospectively analyzed the clinicopathologic, immunophenotypic, and molecular features of five melanomas confined to the lung diagnosed over a 10-year period at a tertiary referral center. Comprehensive clinical, radiologic, dermatologic, ophthalmologic, and gastroenterologic investigations excluded a cutaneous, mucosal, ocular, or visceral primary melanoma in all patients. Histopathologic review, immunohistochemistry, and targeted next-generation sequencing were performed. The series included three men and two women, aged 66-83 years. Four tumors showed predominantly epithelioid morphology and one displayed spindle-cell features with desmoplastic areas. All cases expressed S100 and/or SOX10, whereas expression of conventional melanocytic markers was variable. Targeted sequencing identified BRAF alterations in two cases, NRAS in one, and NF1 in one, with additional alterations involving the TERT promoter, TP53, and CDKN2A. No tumor demonstrated an intraepithelial or intramucosal melanocytic component in the adjacent bronchial mucosa or pulmonary parenchyma. During follow-up, all patients developed progressive disease and none achieved disease-free status. Melanomas confined to the lung harbor canonical MAPK-pathway driver alterations that are not specific to their anatomical origin, and none of the tumors showed an associated in situ melanocytic component. Although their histogenesis remains unresolved, these findings underscore the difficulty of distinguishing genuine primary pulmonary melanoma from metastasis arising from an occult or completely regressed extrapulmonary primary and support an integrated clinicopathologic and molecular diagnostic approach.
Gene fusions have moved from ancillary molecular findings to defining events for an expanding group of neoplasms, with consequences for tumor classification, diagnostic certainty, and, in selected settings, targeted therapy. Yet the practical problem facing pathologists is not simply whether fusion testing is available, but when morphology should trigger it, which assay should be selected, and when conventional testing should be bypassed in favor of RNA-based sequencing. This structured narrative review synthesizes established morphologic, immunohistochemical, and molecular principles into a cross-cutting, tumor-type-agnostic, pathology-centered decision framework. We first summarize morphologic red flags that raise the pre-test probability of a fusion-driven neoplasm, including monomorphic spindle-cell, primitive round-cell, epithelioid/clear-cell, and secretory or salivary-like patterns, as well as unusual age-site combinations and morphology-immunophenotype discordance. We then position immunohistochemistry (IHC) as a triage layer rather than a molecular surrogate in all cases, emphasizing marker specificity, clone- and platform-dependent performance, and the distinction between screening and near-diagnostic surrogate markers. The relative roles of fluorescence in situ hybridization (FISH), reverse-transcription polymerase chain reaction (RT-PCR), DNA-based next-generation sequencing (NGS), targeted RNA-based NGS (RNA-NGS), and whole-transcriptome approaches are compared from a diagnostic decision-making perspective. Particular attention is given to the potential role of direct-to-RNA testing in tissue-limited or fusion-diverse cases, pre-analytical limitations of formalin-fixed paraffin-embedded (FFPE) material, and the interpretation of discordant, novel, or multiple fusion calls. Finally, we propose an expert-derived, hypothesis-generating closed-loop escalation framework in which molecular data resolve morphologic questions rather than replace morphologic reasoning. The framework has not been prospectively validated; its decision thresholds and potential effects on diagnostic yield, tissue use, cost, and time to diagnosis require formal evaluation.
Following a case report in which acute megakaryoblastic leukemia (AMKL) presenting as a soft tissue mass was misdiagnosed as composite hemangioendothelioma due to ERG and CD31 co-expression, we investigated whether this vascular marker co-expression is an isolated phenomenon or a reproducible feature of AMKL and other myeloid neoplasms, with particular relevance to distinguishing extramedullary myeloid neoplasms from vascular tumors. We studied 11 AMKL, 17 myeloid sarcoma (MS), 10 acute myeloid leukemia (AML), 40 chronic myeloproliferative neoplasms (10 each of essential thrombocythemia, chronic myeloid leukemia [CML], primary myelofibrosis, polycythemia vera), 17 myelodysplastic neoplasms (MDS), and 20 non-neoplastic bone marrow samples. ERG and CD31 extent and intensity were evaluated separately in blasts and mature megakaryocytes, and H-scores were analyzed using Kruskal-Wallis and Mann-Whitney U tests with Benjamini-Hochberg correction; ROC-derived cut-offs are presented as exploratory. ERG expression in AMKL blasts was frequent (10/11) and typically extensive, with significantly higher H-scores than MS and AML blasts (p = 0.007 and p = 0.028). ERG was also expressed in most MS cases (12/17). CD31 expression in AMKL blasts did not differ from MS or AML (p = 0.87). In megakaryocytes, ERG was significantly higher in AMKL than in controls combined (p = 0.001), reaching significance against all individual groups except CML and MDS, while CD31 was uniformly expressed. ERG/CD31 co-expression in AMKL and, to a lesser extent, MS constitutes an under-recognized pitfall mimicking vascular neoplasms in extramedullary presentations. Rather than a stand-alone AMKL marker, awareness of this pattern is essential to avoid misinterpretation as angiosarcoma or epithelioid hemangioendothelioma.
Differentiated high-grade thyroid carcinoma (DHGTC) is a recently recognized entity characterized by increased mitotic activity and/or tumor necrosis while retaining the morphological features of differentiated thyroid carcinoma. Data regarding clinicopathological predictors of radioactive iodine (RAI) response in DHGTC remain limited. This retrospective study included 39 patients diagnosed with DHGTC. Clinicopathological parameters including tumor size, multifocality, extrathyroidal extension (ETE), capsular invasion, lymph node metastasis (LNM), lymphovascular invasion (LVSI), and coexistent lymphocytic thyroiditis were evaluated. Response to therapy was assessed during follow-up and categorized as radioiodine-sensitive (RAI-S) or radioiodine-refractory (RAI-R). Associations between clinicopathological variables and RAI response were assessed using Fisher's exact test with univariate odds ratio analysis, followed by multivariable generalized linear modeling. Of the 24 evaluable patients, 15 were RAI-sensitive and 9 developed RAI-refractory disease. Univariate analysis demonstrated significant associations between RAI-refractory disease and tumor size ≥2 cm, ETE, LNM, LVSI, and capsular invasion (all p < 0.05), whereas multifocality and coexistent lymphocytic thyroiditis showed significant inverse associations. ETE exhibited the strongest association with RAI-refractory disease (OR = 24.18, 95% CI: 9.33-58.26; p < 0.0001). Exploratory multivariable analysis demonstrated that extrathyroidal extension remained significantly associated with radioiodine-refractory disease (p = 0.024). DHGTC demonstrates heterogeneous response to radioactive iodine therapy. Extrathyroidal extension showed the strongest association with radioiodine-refractory disease in the present cohort, suggesting its potential utility as a practical marker for risk stratification and follow-up planning. Larger multicentre studies are warranted to validate these findings.
Transbronchial lung cryobiopsy (TBLC) is the standard procedure for diagnosing interstitial lung disease (ILD). However, no morphology-based evaluation method has been established to assess clinical outcomes. Fibroblastic foci (FF), an important histopathological feature of idiopathic pulmonary fibrosis, are also observed in various ILDs, and their distribution may be useful for diagnosis. We examined whether the presence and distribution of FF in TBLC specimens have diagnostic utility and whether these features are associated with pulmonary function decline after TBLC. Among 198 patients who underwent TBLC, 46 with connective tissue disease-associated ILD (CTD-ILD), 53 with fibrotic hypersensitivity pneumonia (FHP), and 42 with idiopathic nonspecific interstitial pneumonia (INSIP) were analyzed to assess the diagnostic significance of FF. To explore whether FF findings were associated with pulmonary function decline across treatment modalities, 114 patients were classified into observation (n = 45), anti-inflammatory/immunosuppressive therapy (n = 50), and antifibrotic therapy (n = 19) groups. FF were classified as peripheral (pFF), alveolar (aFF), centrilobular (cFF), and distorted/dense fibrotic (dFF) lesions. The number of cFF-positive patients and the number of cFF were higher in CTD-ILD and FHP than in INSIP. The number of pFF-positive patients and the number of pFF were significantly higher among patients receiving antifibrotic therapy who experienced a ≥ 10% decline in percent predicted forced vital capacity at the 1-year follow-up after TBLC. Our results suggest cFF were more associated with CTD-ILD and FHP than with INSIP. The presence of pFF warrants further investigation as a potential feature associated with subsequent pulmonary function decline.
SMARCA4-deficient conventional non-small cell lung carcinoma (SMARCA4-dNSCLC) is an aggressive NSCLC subtype with significant phenotypic heterogeneity. We retrospectively examined 110 SMARCA4-dNSCLC patients diagnosed between July 2022 and February 2025, focusing on TTF-1 and P40 expression patterns. The median age was 67 years; 91% were male, 58% had smoking history, and 54% presented at stage IV. Adenocarcinoma was predominant (50%) with marked morphologic heterogeneity, and 85% showed complete BRG1 loss. TTF-1 positivity was found in 31% and P40 in 23%; high PD-L1 expression (TPS ≥50%) occurred in 15%. Among 71 tested patients, 19 had at least one driver alteration (total number of alterations was 24). TTF-1-positive tumors were associated with better overall survival (HR = 0.11, 95% CI: 0.01-0.84, P = 0.034), whereas P40 status alone showed no significant association. Cases with TTF-1-/P40+ or TTF-1-/P40- phenotypes showed poorer survival (P = 0.024). SMARCA4-dNSCLC often presented in male smokers with advanced disease and marked heterogeneity. Retained TTF-1 or P40 expression underscores the need to integrate BRG1 status with morphology and lineage markers.
Gastric heterotopia of the colorectum is rare, and its clinicopathologic spectrum and diagnostic pitfalls remain incompletely characterized. We retrospectively reviewed colorectal gastric heterotopia diagnosed at a single institution from June 2003 through January 2024. Three pathologists independently reviewed the available histologic material, and clinical, endoscopic, ancillary-study, and follow-up data were collected from existing records. Ten cases were identified. Patients ranged from 18 to 78 years of age; six were male and four were female. Four patients were asymptomatic, four presented with gastrointestinal bleeding, and two with nonspecific abdominal pain. All lesions were solitary; eight involved the rectal/anorectal region, and seven were polypoid. Among seven lesions with documented size, the median was 1.2 cm (range, 0.7-3.0 cm). All cases contained well-developed oxyntic glands with parietal and chief cells; foveolar epithelium was present in 9, pyloric glands in 6, goblet cells in 3, and minor salivary gland-type tissue in 1. Tissue identification testing in two detached-fragment cases showed genotype concordance between gastric-type mucosa and native colorectal reference tissue, supporting same-patient origin. No dysplasia or neoplasia was identified. Clinical follow-up was available for eight patients (median, 63 months); persistent gastric heterotopia was documented in one patient, with no dysplasia or malignancy identified during follow-up. These findings expand the clinicopathologic spectrum of this rare lesion and show generally favorable findings during the available follow-up.
Stroma AReactive Invasion Front Areas (SARIFA) is a histopathological pattern of tumor-adipocyte interaction not previously evaluated in melanoma. We aimed to define melanoma-adapted SARIFA criteria and evaluate their associations with dissemination-related histopathological features in fifty Clark level V cutaneous melanomas. SARIFA was defined as direct contact between adipocytes and a cluster of at least five melanoma cells at the invasive front, without intervening stroma or inflammatory reaction. Associations with clinicopathological variables were assessed using the Mann-Whitney U and Fisher's exact tests, and a multivariable model evaluated the SARIFA-lymphovascular invasion association after adjustment for Breslow thickness and ulceration. Reproducibility was assessed using Cohen's kappa. SARIFA was identified in 24 of 50 cases (48%). SARIFA-positive tumors showed greater Breslow thickness (p = 0.015) and more frequent ulceration (p = 0.035), and were associated with lymphovascular invasion (p < 0.001; OR, 10.37; 95% CI, 2.42-56.39) and microsatellitosis (p = 0.015; OR, 7.39; 95% CI, 1.27-79.81). In the multivariable model, SARIFA remained associated with lymphovascular invasion after adjustment for Breslow thickness and ulceration (OR, 7.22; 95% CI, 1.82-33.50; p = 0.0068). Interobserver and intraobserver agreement were substantial (κ = 0.64; 95% CI, 0.38-0.90) and almost perfect (κ = 0.84; 95% CI, 0.69-0.99), respectively. SARIFA was associated with lymphovascular invasion and microsatellitosis, and the association with lymphovascular invasion was maintained in multivariable analysis. Melanoma-adapted SARIFA may represent a reproducible histopathological pattern linked to dissemination-related tumor behavior, although validation in larger cohorts with clinical outcome data is required.
Nuclear STAT6 immunohistochemistry is the diagnostic surrogate for the NAB2::STAT6 fusion of solitary fibrous tumour (SFT); its sensitivity is established, but specificity varies for unexamined reasons. This review quantified pooled accuracy and tested whether antibody clone and nuclear threshold govern specificity. PubMed, Scopus and Web of Science were searched to 29 June 2026 for studies reporting nuclear STAT6 immunohistochemistry against a reference standard (NAB2::STAT6 confirmation and/or expert consensus) in SFT and comparators, with extractable two-by-two data. Two reviewers screened, extracted data and applied QUADAS-2. A bivariate generalised linear mixed model gave summary sensitivity and specificity, and exploratory subgroup analysis and meta-regression tested antibody clone, anatomical site and reference-standard type. Twenty-three studies (1216 SFT and 4715 comparators) were included. Summary sensitivity was 98.7% (95% confidence interval 96.7-99.5) and specificity 99.1% (97.8-99.6); the diagnostic odds ratio was approximately 8656. The monoclonal YE361 subgroup (8 studies) reached specificity 99.9% (99.3-100), with one false positive among 861 comparators, versus 98.1% (96.0-99.1) for polyclonal and other antibodies. False positives concentrated in dedifferentiated liposarcoma and prostatic stromal tumours. Estimates were stable after removing studies at higher risk of bias (98.9%/99.1%) and on leave-one-out analysis; the Deeks test was non-significant (p = 0.08). Nuclear STAT6 immunohistochemistry is therefore highly sensitive and specific for SFT, and the residual specificity loss is structured and largely avoidable: the monoclonal YE361 read at a strict nuclear threshold is preferred, with MDM2 and CDK4 applied to exclude dedifferentiated liposarcoma when nuclear STAT6 is unexpectedly positive.
Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms with variable clinical behavior, ranging from indolent to aggressive. Immunohistochemical data regarding p16 and ß-catenin are conflicting, a direct comparative analysis of both makers has not been carried out and a correlation with the Demicco grading system is missing. A cohort of 30 surgically resected SFTs was analyzed by 11 immunohistochemical markers (p16, p53, Ki-67, PHH3, Cyclin E1, STAT6, ß-catenin, CD34, Vimentin, BCL2, CD99). Results (with a focus on p16 and ß-catenin) were statistically compared with the Demicco grading and available clinicopathological parameters. Three immunophenotypic subgroups were identified: p16+/ β-catenin- (12/30, 40%), p16-/ β-catenin+ (10/30, 33.3%) and double-negative (8/30, 26.7%); co-expression was not observed. The p16+ subtype showed higher Demicco scores, heterogeneous but often increased proliferative activity, frequent p53 alterations and the highest rate of metastases. In contrast, the β-catenin+ subtype occurred exclusively in pleuropulmonary SFTs and was associated with intermediate Demicco scores. Double-negative tumors clustered within the low-risk Demicco category and showed uniformly low proliferation indices. Overall, the three subtypes correlated significantly with Demicco risk classification (p = 0.0088). We identified three SFT subgroups based on p16 and β-catenin expression, which correlate with established Demicco risk categories and tumor localization. These markers may complement existing risk stratification and highlight biologically distinct subsets of SFT. Further studies are warranted to validate their clinical utility, particularly given their reproducibility and ease of implementation in routine diagnostic practice.
Accurate determination of human epidermal growth factor receptor 2 (HER2) status is essential for guiding targeted therapy in breast cancer. Immunohistochemistry (IHC) is routinely used for initial screening. Although reflex FISH testing is recommended for all IHC 2+ tumors, only a subset ultimately demonstrate HER2 amplification. We sought to identify clinicopathologic predictors of HER2 amplification among breast cancers with equivocal HER2 IHC results. A single-institution retrospective review was conducted of breast cancer cases from 2018 to 2024 with HER2 IHC 2+ results and corresponding FISH testing. Demographic and clinicopathologic variables were evaluated using univariate and multivariable logistic regression. Receiver operating characteristic (ROC) analysis, area under the curve (AUC), and Youden Index calculations were used to assess predictive performance and identify optimal Ki-67 thresholds. A total of 417 patients were included in the predictive model analyses. Overall, 16.6% of IHC 2+ cases were HER2 FISH positive. Ki-67 proliferation index was the only independent predictor of HER2 amplification on multivariable analysis (p < 0.05), whereas tumor grade, mitotic index, and ER/PR status were not independently associated. ROC analysis demonstrated moderate discrimination (AUC 0.73). A Ki-67 cutoff of 20% achieved 96% sensitivity, 97% negative predictive value, and a 4% false-negative rate. Tumors with Ki-67 < 20% were almost uniformly FISH negative, while those with higher Ki-67 values demonstrated a progressively increased probability of HER2 amplification. Ki-67 was the strongest independent histopathologic predictor of HER2 amplification among IHC 2+ breast cancers. Although these findings are not intended to replace guideline-recommended reflex FISH testing, they provide a foundation for future development and validation of adjunctive risk-stratification models.
Breast implant-associated squamous cell carcinoma (BIA-SCC) is an exceptionally rare and poorly characterized malignancy that arises from the fibrous capsule surrounding breast implants. Due to its rarity, the clinicopathologic features and optimal diagnostic strategies remain incompletely defined. This report presents two cases of BIA-SCC, correlating clinical, radiologic, cytologic, pathologic, and outcome findings with the existing literature. Both patients presented in their 50s, one to two decades after initial silicone breast implantation, exhibiting breast pain and swelling. Although both initially received silicone implants, implant exchange procedures had occurred during the intervening years. Imaging revealed a peri-implant fluid collection (seroma) with/without parenchymal breast mass. In one case, cytologic analysis of seroma fluid identified squamous cells, a finding consistent with previous reports and supporting the utility of aspiration cytology for triaging suspicious peri-implant lesions. Clinical outcomes varied significantly: one patient developed locally aggressive disease with multiple recurrences within months, necessitating adjuvant radiation therapy and chemotherapy, while the second patient remains free of locoregional recurrence following standard-of-care complete capsulectomy. Given the potentially aggressive behavior of BIA-SCC, in cases of late-onset peri-implant seroma or capsular mass, the presence of squamous cells on aspirate cytology may facilitate early recognition. However, definitive diagnosis requires clinicoradiologic correlation and histopathologic confirmation of invasive squamous cell carcinoma originating from the breast capsule. Increased awareness of BIA-SCC may enable earlier diagnosis and appropriate multidisciplinary management.
Epstein-Barr virus-positive (EBV+) classic Hodgkin lymphoma (cHL) may mimic EBV+ diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS), creating a clinically relevant diagnostic pitfall. We retrospectively reviewed 62 immunocompetent patients with EBV+ large B-cell neoplasms and classified cases into five reproducible pattern-based groups: monomorphic EBV+ DLBCL, polymorphic/immune-environment rich EBV+ DLBCL (polyDLBCL), EBV+ cHL with retained B-cell marker expression, canonical EBV+ cHL, and rare EBV+ mediastinal gray-zone lymphoma. The principal diagnostic challenge was the distinction between polyDLBCL and EBV+ cHL, both of which may contain Hodgkin/Reed-Sternberg-like cells in inflammatory backgrounds. OCT2 was the most informative B-cell marker, but partial OCT2 retention in EBV+ cHL should not alone prompt reclassification as DLBCL. CD20 and CD79a showed substantial overlap, whereas CD15 and IMP3 lacked sufficient specificity. GATA3 expression supported canonical EBV+ cHL, but negativity did not exclude cHL, particularly when the B-cell program was retained. EBER-positive cell-size distribution and EBV latency type (98% were type II) were of limited discriminatory value. Tumor-cell PD-L1 expression was highest in canonical cHL and lower in cHL with B-cell marker retention and monomorphic DLBCL. Clinically, younger patients more often had nodal cHL and favorable outcomes, whereas older patients showed more monomorphic histology, more advanced disease and poorer prognosis. Adverse outcome correlated most strongly with age and EBV lytic reactivation. These findings support an immune-environment-rich EBV-positive large B-cell lymphoma continuum in which strict separation of EBV+ cHL from polymorphic EBV+ DLBCL may not fully reflect the underlying biology.
Crystal-storing histiocytosis (CSH) is rare morphologic manifestation of disease histologically characterized by benign histiocytes, usually numerous, filled with cytoplasmic eosinophilic crystals. More than 200 cases have been reported in the literature. In most CSH cases, affected patients also have a plasma cell neoplasm or B-cell lymphoma. We report a 61-year-old man with a remote history of resected colon adenocarcinoma. As part of surveillance imaging he was found to have a 5.5 cm right ureteral/periureteral mass causing hydronephrosis, multi-station lymphadenopathy and splenomegaly. CT-guided biopsy obtained from the mass showed that ≥95% was composed of sheets of histiocytes containing abundant cytoplasmic crystals. The remainder of the specimen was composed of small lymphocytes and plasma cells. Immunohistochemical analysis showed that the lymphocytes were mostly positive for CD5, CD20 and PAX5, and negative for CD3. The plasma cells were positive for monotypic cytoplasmic kappa, CD138 and MUM1/IRF4, and the histiocytes were positive for CD31, CD68, and CD163, with crystals positive for CD68 and MUM1/IRF4. Subsequent bone marrow evaluation with flow cytometry immunophenotypic analysis showed a small monotypic kappa-positive B-cell population positive for CD5, CD19, CD20 and CD23. These findings support the diagnosis of CSH with immunoglobulin crystals associated with B-cell lymphoma. We review the literature on CSH associated with immunoglobulin crystals and discuss the differential diagnosis.
Bland thyroid follicles are occasionally identified within cervical lymph nodes, raising the differential diagnosis of benign thyroid inclusions versus metastatic papillary thyroid carcinoma. Proposed criteria for benign thyroid inclusions include lack of cytologic atypia, subcapsular or central nodal location, and involvement of only one or two lymph nodes. We observed several cases of fibrosing variant Hashimoto thyroiditis with multifocal thyroid tissue in cervical lymph nodes despite the absence of identifiable primary carcinoma. The pathology archives from 2014 to 2024 were searched for cases of fibrosing variant Hashimoto thyroiditis. Cases were reviewed for occult papillary thyroid carcinoma and thyroid tissue within sampled lymph nodes. IgG4 staining results were recorded. HBME-1, BRAF V600E, and NRAS Q61R immunostains were performed on nodal thyroid tissue. Thirty-six patients were identified (28 females, 8 males; median age 54 years, range 26–83). Increased IgG4-positive plasma cells were present in 29 cases. Lymph nodes were sampled in 23 patients, and thyroid tissue was identified in 8. No primary papillary thyroid carcinoma was identified in 6 of these 8 patients, including 4 in whom the entire thyroid gland was submitted for microscopic examination. HBME-1, BRAF V600E, and NRAS Q61R were negative in all nodal thyroid tissue. Our findings suggest that multifocal thyroid tissue within cervical lymph nodes is relatively common in fibrosing variant Hashimoto thyroiditis. The absence of primary carcinoma in most cases, together with bland cytology and negative immunohistochemical findings, supports the possibility that these represent benign thyroid inclusions that fall outside traditionally accepted diagnostic criteria.
Obtaining tissue from advanced non-small cell lung cancer(NSCLC) patients is difficult, yet mutation testing is crucial for targeted therapy. This study evaluates the clinical utility of serous cavity effusion (SCE) supernatant for multi-gene mutation testing, comparing its performance with cell blocks as a promising liquid biopsy alternative. SCE samples were collected from untreated NSCLC patients. Following the routine cytology and DNA ploidy analysis of the SCE samples, matching supernatant and cell block specimens were prepared and subsequently subjected to multi-gene mutation testing using Amplification Refractory Mutation System PCR (ARMS-PCR). The panel comprised 11 genes covering major variant types across EGFR, ALK, ROS1, BRAF, KRAS, NTRK1/2/3, MET, RET, and HER2. Among the 124 patients who met the inclusion criteria, the overall driver gene mutation rate was 77.42%. Mutation status correlated with DNA aneuploidy, specifically with the average DNA Index (DI) value for the top 20 cells with DI > 2.5 (P = 0.004) and the number of cells with DI > 4.5 (P = 0.022). The detection rate of the supernatant (76.61%) was higher than that of the cell blocks (73.39%), though the difference was not statistically significant (P > 0.05). In samples with a tumor cell proportion < 10%, the supernatant achieved a significantly higher detection rate than cell blocks (53.33% vs. 26.67%). The turnaround time for supernatant testing was also much shorter than that for cell blocks (4.5 h vs. 19.5 h). SCE supernatant is a highly effective, rapid, and valuable complementary specimen for multi-gene driver mutation testing in NSCLC, demonstrating superior clinical sensitivity particularly in low-tumor-content or cytologically negative specimens.
Granulomatous inflammation is frequently encountered in lung and lymph node specimens and represents a diagnostic challenge because diverse infectious, immune-mediated, exposure-related, and neoplastic conditions may produce overlapping histologic patterns. Necrotizing, non-necrotizing, suppurative, foreign body-type, vasculitic, and malignancy-associated granulomas provide important diagnostic clues but are rarely disease-specific. Conventional pathology-based evaluation, including hematoxylin and eosin assessment, special stains, immunohistochemistry, culture, and serologic or antigen testing, remains the foundation of etiologic diagnosis. However, these methods may be limited by low organism burden, prior antimicrobial therapy, small tissue samples, formalin fixation, and broad etiologic heterogeneity. Molecular methods, including targeted polymerase chain reaction, 16S ribosomal RNA sequencing, internal transcribed spacer sequencing, targeted next-generation sequencing, and metagenomic next-generation sequencing, provide complementary tools for pathogen detection and species-level identification. This review summarizes the major histopathologic patterns and etiologic categories of granulomatous inflammation in lung and lymph node specimens and proposes a molecularly enhanced pathology-based algorithm for diagnostic workup. The goal is not to replace morphology with molecular testing, but to use histopathology to guide molecular assay selection and to interpret molecular findings within the appropriate tissue, microbiologic, radiologic, and clinical context.
Formalin-fixed paraffin-embedded (FFPE) tissue is the principal substrate for cancer genomic profiling, yet pre-analytical factors affect nucleic acid quality. In our workflow, transurethral resection (TUR) specimens of bladder urothelial carcinoma are fixed promptly but exposed to electrocautery, whereas robot-assisted radical cystectomy specimens are refrigerated overnight before fixation; we compared nucleic acid quality between these specimen types. We analyzed 56 FFPE primary bladder urothelial carcinoma specimens (33 TUR, 23 cystectomy). DNA quality was assessed by the DNA Integrity Number (DIN) and short-to-long cycle threshold ratio (S/L Ct ratio), and RNA quality by the RNA Integrity Number (RIN) and percentage of RNA fragments ≥200 nucleotides (DV200), with group comparisons, Spearman correlations, and multivariable regression (specimen type, fixation duration, storage time). The median DIN (4.4 vs. 3.8, p = 0.004) and S/L Ct ratio (0.943 vs. 0.894, p < 0.001) were higher in TUR than cystectomy specimens; the RIN was also higher (1.9 vs. 1.7, p = 0.040), though low in both groups, and DV200 did not differ (50.3% vs. 47.7%, p = 0.934). In multivariable analysis, TUR specimen type independently predicted higher DIN (β = +0.460, p = 0.040) and S/L Ct ratio (β = +0.442, p = 0.009), whereas longer storage time independently decreased the S/L Ct ratio (β = -0.513, p < 0.001) and RIN (β = -0.352, p = 0.010). In our institutional workflow, TUR specimens showed higher DNA quality metrics than robot-assisted radical cystectomy specimens subjected to overnight refrigerated pre-fixation delay, whereas this workflow-associated advantage did not clearly extend to DV200-defined RNA fragment-length quality. Storage time was associated with selected aspects of nucleic acid deterioration.
Myoepithelioma-like tumor of the vulvar region (MELTVR) is a rare SMARCB1-deficient mesenchymal neoplasm of adult women that can mimic malignant vulvar sarcomas, particularly epithelioid sarcoma. Although loss of SMARCB1/INI1 expression is a defining feature, the comprehensive genomic landscape of MELTVR remains poorly characterized. We report two cases of MELTVR and performed integrated histopathologic, immunophenotypic, and molecular analyses, including whole-exome sequencing (WES) with copy number assessment and targeted RNA-based fusion testing using the Archer FusionPlex Sarcoma panel. Histologically, both tumors consisted of relatively uniform epithelioid to short spindle cells in solid nests and cords within focal myxoid stroma, with complete loss of INI1 and positivity for smooth muscle markers and focal ER/EMA expression. Genomic profiling demonstrated a quiet molecular background in both cases, with low tumor mutation burden (0.45 and 1.03 mut/Mb) and no pathogenic SNVs/indels in major cancer-associated genes. One case showed a focal homozygous deletion of the SMARCB1 locus at 22q11.2, whereas the other case exhibited INI1 loss without detectable SMARCB1 mutation or copy number loss, suggesting heterogeneous mechanisms of inactivation. CDKN2A copy number remained neutral in both tumors. No canonical sarcoma-associated gene rearrangements, including EWSR1, FUS, PLAG1, or NR4A3, were identified. Together with a review of previously reported cases, these findings support MELTVR as an SMARCB1-inactivated neoplasm with low genomic complexity and highlight the diagnostic value of NGS-based profiling in excluding malignant mimics and preventing overtreatment.
