BackgroundLower respiratory tract infections are a major cause of infant mortality, especially in low- and middle-income countries where conventional autopsies are rarely feasible. Minimally invasive tissue sampling (MITS) offers a practical and acceptable alternative for postmortem diagnosis, yet data on lung histopathological findings from community-based surveillance remain limited. This study aimed to describe lung histopathological findings in infants who underwent MITS within a low-resource community setting.MethodsA community-based mortality surveillance was conducted from November 2020 to June 2021 within a Health and Demographic Surveillance System catchment area. MITS lung tissues were collected from deceased infants younger than 6 months whose families provided consent. Lung tissue cores were processed and examined histopathologically, with hematoxylin and eosin staining performed as required to identify pathological features.ResultsHistopathological abnormalities were evident in 24 specimens, including bacterial/bronchopneumonia, diffuse alveolar damage, amniotic fluid aspiration, and so on. Two neonatal specimens exhibited bacterial pneumonia, and 2 showed bronchopneumonia without identifiable pathogens. Among stillbirths, 4 specimens demonstrated intra-alveolar squames and keratinous debris consistent with amniotic fluid aspiration. Two infants showed DAD indicative of acute respiratory distress syndrome; 1 specimen had nonspecific interstitial inflammation.ConclusionMITS proved valuable in identifying diverse lung pathologies in infants, underscoring the major contribution of respiratory disease to infant mortality in low-resource settings. These findings support MITS as a valuable tool for cause-of-death investigation, with larger studies incorporating molecular diagnostics needed to better define disease burden and guide public health action.
BackgroundSpinal teratomas are exceedingly rare germ cell tumors, accounting for .1%-.5% of all spinal cord tumors, with adult-onset tumors being even more uncommon. Mature teratomas consist of differentiated tissues derived from the 3 embryonic germ layers and may contain a wide variety of adult-type tissue components. Prostatic glandular tissue has been documented in only a very limited number of spinal teratoma specimens, whereas bulbourethral gland tissue has never been reported in this setting.Patient PresentationWe report a 60-year-old male patient who presented with a 7-month history of low back and right lower limb pain, which progressively worsened, along with urinary incontinence for over 3 months. Lumbar magnetic resonance imaging (MRI) revealed an irregular intraspinal space-occupying lesion at the L1 level, measuring approximately 15.0 mm × 16.6 mm × 29.4 mm, which appeared slightly hyperintense on T1-weighted imaging, heterogeneous on T2-weighted imaging, and demonstrated heterogeneous enhancement on contrast administration. The patient underwent microsurgical gross total resection of the tumor. Postoperative pathological examination showed that the tumor was composed of mature tissues derived from all 3 germ layers. Endodermal derivatives included morphologically well-formed prostatic acinar structures (positive for PSA and P504S on immunohistochemistry; the preserved basal cell layer was confirmed by 34βE12 and p63 positivity, supporting a benign prostatic origin) and bulbourethral (Cowper) gland structures (clustered mucinous acini lined by cuboidal to columnar epithelium, mucin histochemistry not performed). Mesodermal derivatives included smooth muscle bundles as well as focal thin-walled vascular spaces and scattered clusters of cells morphologically resembling adrenal zona reticularis cells (polygonal cells with abundant eosinophilic or vacuolated cytoplasm containing scant, finely granular brownish-yellow pigment consistent with lipofuscin; immunohistochemical confirmation was not available, as these cell clusters were not present on deeper sections). Ectodermal derivatives consisted of glial tissue and nerve bundles. The pathological diagnosis was mature teratoma. Postoperatively, the patient's symptoms improved markedly.ConclusionsTo our knowledge, this is the first report of bulbourethral gland differentiation in a spinal teratoma. Other rare findings in this specimen included prostatic glands, focal vascular spaces, and cell clusters resembling adrenal cortical cells. These findings further expand the known histological spectrum of spinal teratomas and suggest that during development and migration, germ cells possess the potential to differentiate into urogenital sinus derivatives and may also give rise to other mesoderm-derived lineages. Complete surgical resection remains the mainstay of treatment, and long-term imaging follow-up is essential for monitoring recurrence.
Both embryonic-type neuroectodermal tumor and nephroblastoma arising as somatic-type malignancies are rare, particularly nephroblastoma. Concurrent embryonic-type neuroectodermal tumor and nephroblastoma have only been reported once in literature, identified in metastatic pelvic lymph nodes in association with a mixed germ cell tumor. Herein, we report the first concurrent embryonic-type neuroectodermal tumor and nephroblastoma within the primary testicular tumor, arising associated with a mixed germ cell tumor. A 36-year-old man presented with a 4.5 cm right testicular mass. He underwent right orchiectomy. Gross examination revealed a well-circumscribed, solid to cystic mass confined to the testis (pT1). Histological examination demonstrated a mixed germ cell tumor composed of teratoma (40% of the tumor mass), seminoma (10%), embryonal carcinoma (2.5%), and yolk sac tumor (2.5%), with associated germ cell neoplasia in situ. Additionally, two somatic-type malignancy components were identified, including embryonic-type neuroectodermal tumor (40%) and nephroblastoma (5%). The embryonic-type neuroectodermal tumor consisted of primitive neural tubules, rosettes, and blastemal cells. The nephroblastoma was composed of tubules, blastemal cells, and stromal cells. Immunohistochemically, the embryonic-type neuroectodermal tumor showed diffuse positivity for SOX11, with focal expression of synaptophysin and CD99, while the nephroblastoma was positive for PAX8 and WT1. The patient developed metastasis to a retroperitoneal lymph node 1 month after the orchiectomy, subsequently received chemotherapy, and is alive without metastatic disease at 13 months of follow-up.
Adenoid cystic/basal cell carcinoma (ACBCC) of the prostate is a rare tumor, with only about 100 tumors reported in the literature. We present a 66-year-old man with incidental finding of prostatic cancer duplicity-ACBCC of the prostate and prostatic acinar adenocarcinoma in radical prostatectomy specimen. Prostatic acinar adenocarcinoma was of Gleason score 6 (3 + 3), focally present at surgical margin, exhibited perineural invasion but no extraprostatic extension. Concurrently, ACBCC was detected, the tumor exhibited adenoid cystic-like morphology, with multifocal involvement of the resection margins and extraprostatic extension. This coincidence presented a unique opportunity to comprehensively examine the molecular characteristics of both tumors. SETD2 mutation was identified in ACBCC, while it was absent in acinar adenocarcinoma. No significant differences were detected by other genetic analyses, and both tumors clustered together within "Prostatic adenocarcinoma" control group and separated from adenoid cystic carcinoma of other locations using methylation profiling.
We report a bronchiolar adenoma of the lung with unusual features. A 68-year-old woman presented with a right lower lobe lung mass found during routine screening. Positron emission tomography studies revealed a metabolically active 5.4 cm lesion. The patient underwent an endoscopic ultrasound-guided transbronchial fine needle aspiration. The cytologic material was interpreted as a basaloid neoplasm of uncertain malignant potential; focally, the cytologic features resembled adenoid cystic carcinoma. A lobectomy revealed a circumscribed biphasic tumor, composed of luminal epithelial cells and subjacent basal cells. The luminal cells consisted of ciliated cells and type II pneumocytes expressing CAM 5.2, TTF1, and NAPSA (napsin A aspartic peptidase). The basal cells were associated with a weakly basophilic matrix and basement membrane-like material; these cells expressed TP63 and expressed weakly with CAM 5.2 and calponin (CNN1). The tumor did not invade the pleura and did not show vascular or perineural invasion. The histopathologic and immunohistochemical findings, as well as the BRAF-V600E mutation supported its classification as an unusual variant of bronchiolar adenoma showing a prominent basement membrane-like material. This tumor was incidentally associated with a lung adenocarcinoma in situ. This presentation describes an unusual variant of bronchiolar adenoma and underscores the value of integrating the cytologic, histologic, and molecular findings.
Background/ObjectivesSpitz nevus with architectural features of a Clark/dysplastic nevus ("SPARK nevus") is an uncommon melanocytic lesion closely mimicking dysplastic nevus and melanoma, creating diagnostic challenges. This study aimed to delineate the clinical, histopathologic, and immunohistochemical features of SPARK-pattern lesions and to clarify their biologic behavior.MethodsA multi-institutional retrospective study across six academic centers identified 74 SPARK nevi. Candidate lesions were re-reviewed at each institution by board-certified dermatopathologists using predefined inclusion criteria requiring concurrent Spitzoid cytology and Clark-type architectural features. The demographic, clinical, histologic, immunohistochemical, and follow-up data were collected and reviewed.ResultsThe cohort showed a predominance of female patients (76%) with a mean age of 32.4 years (range 11-68), and lesions were small (mean diameter 5.8 mm, range 2-20 mm), most often on the proximal extremities and trunk. Histologically, lesions were mainly compound (70%) with Spitzoid cytology in Clark-type architecture; cytomorphology was mixed epithelioid-spindled (47%) or epithelioid (41%), Kamino bodies were infrequent (9%), inflammation was usually non-brisk (62%), and cytologic atypia often reached moderate to severe grades. Immunohistochemistry (performed in 55%) showed PRAME negativity, retained p16, and low MKI67 indices, and follow-up (available in 93%; median 18 months) revealed one local recurrence, two metachronous SPARK nevi, and no SPARK-related deaths.ConclusionsThis largest series defines the clinicopathologic and immunohistochemical spectrum of SPARK-pattern lesions and demonstrates overall benign behavior despite morphologic overlap with dysplastic nevi and melanoma. SPARK is most appropriately interpreted as a morphologic pattern encompassing lesions arising from multiple melanocytic pathways.
Myoepithelial carcinoma is an uncommon malignant tumor of neoplastic myoepithelial cells. Myoepithelial carcinoma may arise in salivary glands or within soft tissues, and myoepithelial carcinomas of salivary and soft tissue types are generally regarded as distinct. Fusions involving EWSR1 are a molecular hallmark of soft tissue myoepithelial carcinomas; however, salivary myoepithelial carcinomas typically lack these fusions. We report an unusual high-grade myoepithelial carcinoma arising in the submandibular gland of a man in his 20s, initially diagnosed as extraskeletal Ewing sarcoma due to an EWSR1 rearrangement identified by fluorescence in situ hybridization (FISH). The resection specimen demonstrated a round cell tumor with multiple growth patterns and high-grade features. No benign pleomorphic adenoma component was identified. Tumor cells were positive for pankeratin, S100, and SOX10, and were only weakly positive for CD99. Next-generation sequencing unearthed an EWSR1::CREB1 fusion, which has been identified in a handful of diverse soft tissue neoplasms. While EWSR1 signal rearrangements by FISH have been described, a bona fide fusion involving EWSR1 is novel, if this tumor does indeed represent a myoepithelial carcinoma of salivary origin. No primary salivary tumors with a CREB1 fusion partner have been described. We highlight the possibility that myoepithelial carcinoma may arise within the major salivary glands, and that definitive distinction between salivary myoepithelial carcinoma and soft tissue myoepithelial carcinoma is quite difficult, even with molecular data.
BackgroundPrimary squamous cell carcinoma of the breast is an extremely rare subtype of metaplastic breast carcinoma, often showing aggressive clinical behavior and posing diagnostic challenges, particularly when acantholysis is present and mimics vascular neoplasms.Patient presentationWe report a 49-year-old woman presenting with a rapidly growing palpable mass in the outer quadrant of the left breast. Initial cytology yielded keratin debris interpreted as benign. Following inflammatory changes, the lesion was excised with a clinical pre-diagnosis of granulomatous mastitis. Gross examination revealed an 8 × 7 × 7 cm partial mastectomy specimen containing a 6 × 5 × 4 cm firm, cystically and hemorrhagically degenerated, irregularly circumscribed tumor adjacent to but not continuous with the overlying skin. Microscopically, the tumor consisted of infiltrating nests of squamous epithelial cells with widespread acantholysis and single-cell keratinization, moderate nuclear atypia, and absence of lymphovascular or perineural invasion. Associated ductal carcinoma in situ was identified. Immunohistochemically, the tumor cells expressed pan-keratin, keratin 5/6, keratin 14, p63, CD10 (MME), and EGFR, while ER, PR, HER2, and GATA3 were negative. Ki-67 (MKI67) proliferation index was approximately 10%. Final diagnosis was primary acantholytic squamous cell carcinoma of the breast.ConclusionThis patient highlights the importance of thorough histopathologic and immunohistochemical evaluation to distinguish acantholytic squamous cell carcinoma of the breast from vascular mimics and other metaplastic carcinomas. The basal-like, hormone-receptor negative, HER2-negative, and low proliferative profile in this tumor underscores the heterogeneity of primary squamous cell carcinoma of the breast and the need for individualized treatment strategies.
Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder originating from dendritic cells and primarily occurring in children. Although pulmonary LCH is relatively common among adult smokers, isolated mediastinal involvement is very rare. This study reports a 33-year-old female patient who presented with a 2-month history of right upper back pain. Positron emission tomography/computed tomography revealed an isolated 6.2 × 3.5 cm mixed-density mass in the right anterior mediastinum, raising suspicion for invasion of the pericardium, major vessels, and diaphragmatic pleura. However, during surgical resection, the lesion appeared well-encapsulated, with no evidence of invasion. This discrepancy was explained by postoperative histopathology, which revealed prominent thymic hyperplasia containing a small 3 mm focus of LCH. This rare presentation of isolated anterior mediastinal LCH in an adult highlights potential for radiologic overestimation when a small LCH focus is accompanied by prominent thymic hyperplasia, underscoring the need for careful individualized evaluation.
ObjectiveAtypical microglandular hyperplasia (MGH) of the cervix with a pseudoinvasive pattern is a well-known diagnostic pitfall. This study reviews this entity and uses two initially misdiagnosed lesions to illustrate the key morphologic, immunohistochemical, and molecular features that distinguish atypical MGH from its malignant mimics. The aim is to provide a practical diagnostic framework to improve diagnostic accuracy and prevent patient overtreatment.MethodsWe conducted a retrospective clinicopathological analysis of two patients with atypical cervical MGH exhibiting a pseudoinvasive pattern. Diagnosis was confirmed through comprehensive histological examination, supplemented by immunohistochemistry, special staining (Alcian blue-periodic acid-Schiff), and molecular testing for KRAS mutations. Clinical follow-up was obtained, and relevant literature was reviewed.ResultsThe patients were a 54-year-old woman and a 47-year-old woman presenting with irregular vaginal bleeding. Both lesions were initially misdiagnosed at outside institutions (as endometrial adenocarcinoma and usual-type endocervical adenocarcinoma, respectively). Histological review revealed nearly identical features: a complex proliferation of small, crowded microglandular structures, intermixed with irregular solid nests and cords of cells with eosinophilic cytoplasm, haphazardly dispersed in a loose, myxoid stroma. Occasional signet-ring-like cells were noted. Immunohistochemically, the lesions were positive for ER (estrogen receptor, official symbol ESR1), showed focal p16 (CDKN2A) positivity, a wild-type p53 (TP53) pattern, and a low Ki-67 (MKI67) index (≈2%). They were negative for CEA (CEACAM5), with retained expression of PTEN and PAX2. Alcian blue-periodic acid-Schiff staining was positive. No KRAS mutations were detected.ConclusionCervical MGH is a benign lesion, but its atypical variant with a pseudoinvasive pattern is a great mimicker of adenocarcinoma. A definitive diagnosis requires the integration of characteristic histomorphology with a confirmatory immunohistochemical profile. Pathologists must be familiar with this entity to avoid misdiagnosis and ensure appropriate clinical management.
Undifferentiated/dedifferentiated melanomas typically lack all conventional melanocytic biomarkers and closely mimic non-melanocytic malignancies, risking misclassification and missed melanoma-directed therapy. We report four metastatic undifferentiated/dedifferentiated melanomas from 3 women and 1 man (median age 67 years) to genitourinary (GU) sites, involving the adrenal gland (n = 2), kidney (n = 1), and perirenal soft tissue (n = 1). Resected tumors (n = 3; median 5.4 cm) and one biopsy specimen showed high-grade epithelioid and/or spindle-cell morphology with brisk mitotic figures. All four tumors were S100/SOX10/MelanA/HMB45 negative. PAX8 was also negative. In contrast, pan-keratin/CAM5.2/cytokeratin AE1/AE3 and/or p63 showed focal/multifocal staining in all resected tumors. Additional pitfalls included focal weak TFE3 and scattered cathepsin K expression. PD-L1 was diffusely positive (70%-100% of tumor cells) in 2 tested tumors. Targeted next-generation sequencing showed a MAPK-pathway driver in all tumors: BRAF class-3 (D594N, G466R) in 2/4 tumors, NRAS Q61R in 1 tumor, and NF1 truncation (R440*) in 1 tumor, with frequent co-events (TERT promoter mutations; CDKN2A loss; TP53 mutation). UV mutational signatures and high tumor mutational burden supported cutaneous origin. One patient showed clonal continuity between a prior liver metastasis and the subsequent adrenal gland lesion. All patients received PD-1-based immunotherapy (pembrolizumab n = 3; nivolumab n = 1). Three patients achieved complete responses and remain alive and disease-free (median follow-up 28 months; range, 1.8 months-10.5 years), while one patient was lost to follow-up at 2 months with progressive disease. Accurate recognition of these metastatic tumors enables effective therapy. To our knowledge, this is the first dedicated series of GU-site specific undifferentiated/dedifferentiated melanoma and provides a framework for work-up and management.
BackgroundSarcomatoid carcinoma of the prostate is a rare and aggressive biphasic malignancy, typically arising in the setting of prior prostatic adenocarcinoma. Prominent heterologous differentiation may obscure its epithelial origin and lead to diagnostic confusion with primary mesenchymal tumors.Case presentationWe report an 80-year-old man with a history of metastatic prostate adenocarcinoma treated with androgen deprivation therapy, who presented with acute urinary obstruction and low prostate-specific antigen levels. Transurethral resection revealed a highly heterogeneous tumor composed of extensive cartilaginous and high-grade sarcomatoid components, including both chondrosarcomatous and osteosarcomatous differentiation. Despite thorough histopathological examination, no epithelial component was identified. Prior pathology confirmed adenocarcinoma up to 9 months earlier, with evidence of sarcomatoid transformation emerging in recent specimens. Immunohistochemistry supported mesenchymal differentiation. Based on clinicopathological correlation, a diagnosis of sarcomatoid carcinoma of the prostate with heterologous differentiation was established.ConclusionThis report highlights a significant diagnostic pitfall in which sarcomatoid carcinoma may mimic primary sarcoma when the sarcomatoid component predominates and epithelial elements are absent. It also underscores the potential role of androgen deprivation therapy in tumor dedifferentiation and the limitations of PSA in monitoring disease progression. Awareness of this entity is essential for accurate diagnosis and appropriate clinical management.
In patients with squamous cell carcinoma of the head and neck, co-occurring chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is not uncommon. Given the often subtle histopathologic features, this diagnosis may go unrecognized by the pathologist. This study aims to investigate the high rate of co-occurrence of CLL/SLL and head and neck squamous cell carcinoma and to illustrate the combination of clinical and histopathologic findings in these patients. A retrospective single-institution review was conducted of 3524 pathologic diagnoses of head and neck squamous cell carcinoma, from which 24 patients with concurrent diagnoses of CLL/SLL were identified. Squamous cell carcinomas for these 24 patients were restaged, and the histopathologic and immunohistochemical profiles were assessed. Concurrent cutaneous squamous cell carcinoma was identified in 21 out of 24 patients, with oropharyngeal squamous cell carcinoma in the remaining 3. Nine patients had nodal metastases. Fine-needle aspiration biopsy was performed in 15 out of 24 patients and rendered the diagnosis of squamous cell carcinoma in 9 patients and CLL/SLL in 6 patients. Co-occurring CLL/SLL is easily missed in biopsies and neck dissections performed for the diagnosis and management of head and neck squamous cell carcinomas. Awareness of the pertinent morphologic features should prompt additional immunohistochemical studies that can lead to a definitive diagnosis.
Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) is typically characterized by MDM2 and/or CDK4 amplification. However, a subset lacks these alterations, suggesting alternative oncogenic drivers. We report a patient with recurrent retroperitoneal WDLPS who developed multiple relapses over more than 25 years. Histology demonstrated a well-differentiated morphology with extensive myxoid change, without evidence of dedifferentiation. Molecular profiling using next-generation sequencing (NGS) identified MDM4 amplification, together with mutations in PIK3CA and TERT. This finding supports MDM4 as a potential alternative driver in liposarcomagenesis, possibly correlating with a more indolent clinical course. Recognition of this rare alteration is important for accurate diagnosis and may have future therapeutic implications.
Esophageal squamous cell carcinoma with ductal differentiation (ESCC-DD) is exceedingly rare. This article presents a 61-year-old man with progressive dysphagia. Imaging studies and endoscopy were suggestive of malignancy. Pathological examination of the biopsy specimen diagnosed squamous cell carcinoma with focal biphasic glandular structures. The patient received chemotherapy with albumin-bound paclitaxel plus cisplatin, combined with immunotherapy using sintilimab injection, alongside supportive care to manage treatment-related adverse effects. One month later, his dysphagia had significantly improved. Post-treatment imaging showed reduced wall thickening in the mid-to-lower thoracic esophagus. The patient subsequently underwent thoracoscopic-laparoscopic esophagectomy. The postoperative pathological diagnosis was “esophageal carcinoma post comprehensive treatment,” specifically moderately differentiated squamous cell carcinoma with focal biphasic glandular structures infiltrating the muscularis propria. The primary tumor site showed a minimal treatment response (Grade 2 according to the Becker criteria) on tumor regression grading, with approximately 15%-20% residual carcinoma cells within the tumor bed, along with stromal fibrosis and a prominent inflammatory infiltrate. Regional lymph nodes were positive for metastatic carcinoma. The histogenesis of the bilayer glandular structures found in ESCC remains a subject of debate. Based on immunohistochemical and special staining, we speculate these glands originate from aberrant differentiation of multipotent stem cells within esophageal submucosal gland ducts. We provide a comprehensive analysis of the histopathological features, clinical behavior, treatment, and prognosis of ESCC-DD.
Following the recent first report of a posterior mediastinal Müllerian cyst in a male patient (Mihara et al, 2026), we present the second documented male patient, confirming that this entity, previously considered exclusive to women since the 2005 description by Hattori, can indeed occur in men. A 51-year-old man was incidentally found to have a posterior mediastinal cyst during cardiac computed tomography. The 3.5 × 3 × 5.5 cm3 cyst at T4-T7 was resected via robotic-assisted thoracoscopy. Immunohistochemistry confirmed Müllerian differentiation (estrogen receptor+/progesterone receptor+/PAX8+/WT1+). This second male patient establishes that posterior mediastinal Müllerian cysts should be considered in the differential diagnosis of mediastinal cystic lesions regardless of patient sex.
Malignant peripheral nerve sheath tumours (MPNST) are aggressive soft tissue sarcomas. The occurrence of MPNST of the adrenal gland is exceedingly rare with only two other de-novo tumours reported in literature. It has been reported to be associated in some patients with neurofibromatosis type-1 and composite tumours like pheochromocytomas and ganglioneuromas. There are no reports of an MPNST presenting as an adrenal incidentaloma. It is impossible to achieve a pre-operative diagnosis. Diagnosis depends solely on histopathological identification. Loss of H3K27me3 trimethylation can be helpful in distinguishing these tumours from possible mimics and is associated with higher tumour grade and more aggressive clinical behaviour.
Collagenous colitis-like amyloid deposition in the gastrointestinal tract is an uncommon pattern of gastrointestinal amyloidosis. This pattern is usually associated with AA-amyloid. The recognition of this pattern is difficult for an unaware pathologist. We report collagenous colitis-like deposition of AA amyloid in a 45-year-old woman at the time of autopsy. The woman suffered from antisynthetase syndrome-systemic lupus erythematosus overlap syndrome-was on continued immunosuppression and presented with fever, watery diarrhea, and vomiting. The amyloid showed a band-like congophilic subepithelial deposition throughout the large intestine and terminal ileum. This pattern of amyloid deposition can be distinguished from collagenous colitis by its pale blue-green color on Masson trichrome stain, frayed/fuzzy edges, congophilia with apple-green birefringence, and SAA-positivity.
Objectives Leiomyosarcoma of the inferior vena cava (IVC-LMS) is a rare vascular sarcoma that typically spreads hematogenously, while lymphatic dissemination is exceedingly uncommon. This report presents the first histologically confirmed patient with regional lymph node metastasis in leiomyosarcoma of the IVC detected at the time of initial surgery. Methods A 60-year-old woman presented with abdominal and back pain. Preoperative imaging revealed a retroperitoneal mass encasing the IVC, initially suspected to be lymphoma. The patient underwent en bloc resection of the tumor with the IVC and aortic graft replacement. Histopathologic and immunohistochemical analyses were performed to confirm tumor type and assess lymphatic involvement. Results Histology showed spindle-shaped tumor cells with nuclear pleomorphism and positivity for desmin and α-smooth muscle actin, confirming leiomyosarcoma. A regional lymph node exhibited metastatic infiltration, verified by hematoxylin and eosin and D2-40 immunostaining. Despite complete resection, the disease recurred within 2 weeks and metastasized to the lungs, liver, and peritoneum within 5 months. The patient died 11 months after surgery. Conclusions This report provides the first histologic evidence of lymphatic metastasis in leiomyosarcoma of the IVC, challenging the traditional view that lymphatic spread is negligible in this disease. Selective lymph node evaluation may improve staging accuracy and guide surgical planning for high-risk patients.
The International Classification of Diseases for Oncology (ICD-O) behavior code for pituitary neuroendocrine tumors (PitNETs) underwent a historic shift from "/0" (benign) to "/3" (primary malignant) in the 2022 fifth edition of the WHO classification. This coding change is not a mere terminological substitution but represents a profound reconceptualization of the biological nature of PitNETs-transitioning from the classical paradigm of "indolent benign adenoma" to a novel framework of "full-spectrum neuroendocrine tumors with malignant potential." This article systematically reviews the historical context and driving forces behind the evolution of the ICD-O code from /0 to /3. It then elaborates on the molecular advances underpinning this coding change across three levels: genetic mutations, epigenetic remodeling, and post-transcriptional regulation. Crucially, it emphasizes that the clinically validated morphologic subtyping, which has proven prognostic value, often but not always correlates with these molecular alterations, and remains the cornerstone of patient management. Finally, it discusses unresolved issues in the current classification system and future directions. In conclusion, the transition of the ICD-O code from /0 to /3 marks a critical milestone in PitNET taxonomy, signifying its shift from a "histological" paradigm, where molecular insights complement, but do not replace, a precise morphologic classification.
