ABSTRACT Background Leptomeningeal carcinomatosis (LC) in patients with disseminated cancer has a grave prognosis and limited therapeutic options. Diagnosis is delayed due to low CSF volume and scant cellularity. This quality improvement project was undertaken to evaluate the diagnostic performance of CSF cytology in cases with radiologic evidence and the utility of immunohistochemical (IHC) testing in stratifying atypical cases. Methods A 5 years retrospective review of CSF cytology, oncology notes, and MRIs from patients with non‐hematologic malignancy and clinical evidence of LC was performed. A total of 39 CSF samples from 28 patients with carcinomas were identified. Cytospins were prepared, and IHC was ordered at the discretion of the pathologist. Root cause analysis was applied to examine factors contributing to equivocal results. Results Of the 39 CSF samples, 49% were classified as positive for malignancy on CSF cytology, 12 as atypical/suspicious, and 8 as negative. Sixteen samples underwent IHC analysis, 11 of which confirmed the positive cytology results. IHC stains were performed only in 2 of the 12 atypical cases. Root cause analysis identified several contributors to diagnostic limitations: (1) small CSF volumes divided across multiple tests; (2) hypocellularity; (3) absence of standardized protocols for IHC use; and (4) pathologist reluctance to order IHC on cytology smears. In all cases where performed, IHC findings correlated with clinical and radiologic impressions. Conclusions This project highlights limitations of CSF cytology alone in diagnosing LC and demonstrates that adjunctive IHC testing improves diagnostic accuracy. Incorporation of IHC into routine evaluation of equivocal cases should be considered.
ABSTRACT Chondromyxoid fibroma (CMF) is a rare, benign cartilaginous tumor composed of myxoid and fibrous components, accounting for approximately 1% of all bone tumors. It typically arises in the metaphysis of long bones, with epiphyseal involvement of the short tubular bones of the hand and foot being uncommon. We report the case of a 14‐year‐old girl who presented with pain and a gradually progressive swelling of the left great toe, occurring after a fracture sustained 2.5 years earlier. Radiological findings were suggestive of an aneurysmal bone cyst or giant cell tumor. Fine‐needle aspiration cytology (FNAC) revealed hypercellular smears comprising pleomorphic oval to spindle‐shaped cells along with dense, pink osteochondroid material; the cytological diagnosis was rendered equivocal, and malignancy could not be excluded. Subsequent histopathological examination showed a well‐circumscribed tumor with a lobular architecture composed of alternating hypocellular and hypercellular areas of myxomatous stroma and immature cartilaginous cells, confirming a diagnosis of chondromyxoid fibroma. Although a low‐grade tumor, CMF may show nuclear atypia histologically and can mimic chondrosarcoma; distinguishing between the two is of paramount importance to avoid over‐diagnosis and unnecessarily aggressive treatment of this benign entity. Complete surgical resection with long‐term follow‐up remains the mainstay of management, given the relatively high rate of recurrence.
ABSTRACT Background The International Academy of Cytology (IAC) recently introduced the Yokohama System (IAC‐YS) for reporting breast fine‐needle aspiration biopsy (FNAB) cytology. The Working Group on the Accuracy of Breast Fine‐Needle Aspiration Cytology of the Japanese Society of Clinical Cytology aimed to categorize breast FNAB specimens according to the IAC‐YS, assess the risk of malignancy (ROM) for each category, and evaluate the diagnostic yield of breast FNAB in Japan. Methods Breast FNAB specimens obtained between January 2010 and December 2019 from nine cooperating facilities were retrospectively reclassified following the IAC‐YS. The ROM for each category was calculated and compared with that using the conventional Japanese diagnostic system (CJS). Diagnostic yield was evaluated using a five‐category approach to distinguish benign from malignant samples. Results In total, 1727 samples from 1722 patients were distributed as follows: Category 1 (insufficient material), 21.3%; Category 2 (benign), 38.9%; Category 3 (atypical), 6.9%; Category 4 (suspicious for malignancy), 10.0%; and Category 5 (malignant), 23.0%. Histological follow‐up was available for 856 cases (49.5%). The ROM was 13.1%, 4.8%, 26.9%, 84.3%, and 94.5% for Categories 1–5, respectively. Conclusions IAC‐YS showed a higher proportion of cases of Category 1 and a lower proportion of cases of Category 3 than the CJS. Despite these differences, both systems were equivalent in their impact on daily medical care, although ROM differed for the content of Categories 1 and 3. Quality assurance parameters for our data based on IAC‐YS are comparable to those of CJS.
ABSTRACT Striated duct adenoma (SDA) is a rare benign salivary gland neoplasm with limited cytologic characterization. We report a case of SDA with cytologic, histologic, immunohistochemical, and molecular correlation to further define its morphologic spectrum and diagnostic considerations. The patient was a 62‐year‐old male with a submandibular gland mass. Cytologically, the specimen demonstrated loose clusters of monomorphic epithelial cells ranging from cuboidal to rare elongated or slightly spindled morphology, with moderate amounts of variable oncocytic cytoplasm. Nuclei were ovoid and normochromatic with occasional nuclear grooves and infrequent pseudoinclusions. No significant nuclear atypia, mitotic activity, necrosis, or stromal components were identified. Using the 2nd Edition Milan System Classification, the case was categorized as Neoplasm: Benign (Category IVA). Histologic examination confirmed SDA, and next‐generation sequencing identified an IDH2 p.R172M mutation. The cytologic and histologic features of SDA overlap with other salivary gland neoplasms, especially those with oncocytic/oncocytoid features. Definitive classification relies on histopathologic correlation and, when available, supportive molecular evidence of an IDH2 mutation.
ABSTRACT Fluid overload‐associated large B‐cell lymphoma (FO‐LBCL) is a distinct entity introduced in the 5th edition of the WHO Classification of Hematolymphoid Tumors (2022). It denotes a large B‐cell lymphoma confined to one or more serous cavities as effusions, without a solid or nodal mass, in the absence of KSHV/HHV8 (and largely EBV) infection, arising in patients with fluid‐overload states. It was previously reported under descriptive terms such as “HHV8‐negative primary effusion lymphoma‐like lymphoma.” We describe two cases illustrating the WHO‐HAEM5 diagnostic criteria and the diagnostic and prognostic workup of this entity.
