International Journal of Surgical Pathology最新文献

TFE3-rearranged perivascular epithelioid cell tumors (PEComas) of the kidney are rare, with fewer than 50 examples reported in the literature. A 32-year-old man presented with an 8.2 cm right renal mass and bulky retroperitoneal lymphadenopathy, raising concern for lymphoma versus renal cell carcinoma (RCC). An initial renal biopsy performed at an outside institution was diagnosed as "RCC, favor chromophobe type," based on morphological features and KIT positivity. Due to limited tumor cells in the initial biopsy for additional studies, a repeat renal biopsy and a biopsy of a right retroperitoneal lymph node were obtained at our institution. Both specimens revealed nests and sheets of epithelioid tumor cells with abundant granular eosinophilic to clear cytoplasm and a perivascular growth pattern. Focal areas showed prominent cell membranes, and melanin pigment was identified in rare tumor cells. Immunohistochemical staining demonstrated strong, diffuse nuclear positivity for TFE3, as well as positivity for HMB45, cathepsin K, and KIT. The tumor cells were negative for pan-keratin, keratin 7, PAX8, CA9, CD10, and SMA. A next-generation sequencing-based fusion assay identified an SFPQ::TFE3 gene fusion. The tumor was classified as a TFE3-rearranged PEComa. The patient underwent systemic therapy followed by radical nephrectomy. The tumor invaded the renal sinus fat and showed extensive lymphovascular invasion (ypT3aN1). Despite treatment, restaging imaging at the 16-month follow-up revealed liver metastases. Subsequent imaging demonstrated further progression, and the patient ultimately opted for supportive care at 32 months. This report highlights the diagnostic challenges of renal TFE3-rearranged PEComas, due to their rarity and overlapping morphologic, immunophenotypic, and molecular features with other neoplasms.

Primary neuroendocrine tumors (NETs) of the genitourinary tract are rare entities encountered in the kidneys, bladder, prostate, testes, and ovaries. Information on grading, biologic behavior, molecular characteristics, and treatment options is lacking. We present two patients with primary NETs which include one lesion involving the testis and one lesion involving the kidney. The testicular NET was incidentally discovered and clinically thought to be a conventional germ cell tumor. Histologically, the tumor was low-grade with pure carcinoid morphology, and did not demonstrate a concurrent teratoma or germ cell neoplasia in situ. Other differential diagnoses like metastasis from an extratesticular primary and sex cord-stromal tumors were argued against. Pure testicular NET is thought to be a prepubertal-type monodermal teratoma that generally lacks isochromosome 12p. Secondly, we report a primary renal NET which metastasized to the liver, lymph node, and bone. No other primary site of origin was identified. The tumor had atypical features including 6 mitotic figures/10 high-power field, Ki67 index of 4%, and resistance to chemotherapy. Prior reports have shown loss of heterozygosity on chromosome 3p21, with mutations in CDH1, TET2 and other genes in a subset of these tumors. However, our molecular assessment showed an alteration involving the ERCC2 gene in this tumor that has been described as a pathogenic variant in autosomally recessive conditions. These lesions highlight the need for urologists and pathologists to recognize and include NETs at unusual locations in their diagnostic consideration.

Myoepithelial tumors are typically characterized by distinct molecular profiles that have been shown to correlate with their anatomical locations. EWSR1 or FUS rearrangements are common in cutaneous, soft tissue and bone tumors, whereas salivary gland myoepithelial tumors are frequently associated with PLAG1 and HMGA2 alterations. This apparent molecular divergence led some previous studies to doubt a common pathogenetic relationship between myoepithelial tumors of soft tissue and bone with their salivary gland counterparts. Herein, we present primary intraosseous myoepithelioma harboring HMGA2::WIF1 fusion. This fusion has been previously identified in a range of salivary gland myoepithelial tumors including myoepitheliomas, myoepithelial carcinomas arising from pleomorphic adenomas, and pleomorphic adenomas themselves. Primary myoepithelial tumors of the bone are exceedingly rare, and to our knowledge, HMGA2 rearrangements have not been previously reported in soft tissue or bone myoepithelial neoplasms. Through this report, we aim to enhance the existing literature on myoepithelial neoplasms, while highlighting the importance of recognizing primary bone myoepitheliomas and contributing to a broader understanding of the pathogenetic landscape of myoepithelial tumors across diverse tissue types.

Intraocular paraganglioma is a very rare tumor. There have only been 4 reports of this tumor location in the literature, which arose in the choroid and iris. We present a patient with an intraocular paraganglioma masquerading as an ocular melanoma, clinically and radiographically, that required careful histological and immunohistochemical analysis for differentiation. Due to the sparse reports, we feel documentation of this patient, as well as a review of previous presentations, is necessary to contemplate clinicopathological correlations.

Micronodular thymic carcinoma with lymphoid hyperplasia (MNC) is an extremely rare tumor. Fewer than 30 histologically proven examples of MNC have been described in the English literature. A 64-year-old man with a history of colon cancer presented with an anterior mediastinal mass on follow-up examination. Surgical excision was performed. Macroscopically, the mass (3.0 × 2.7 cm) was relatively well-demarcated and surrounded by fat. The cut surface was tan yellow and solid. Microscopically, it showed multiple small tumor islands composed of frankly malignant epithelial cells with pleomorphism and increased mitotic activity. They were arranged in a micronodular growth pattern and surrounded by lymphoid stroma composed of CD3-positive small T-lymphocytes and CD20-positive B-lymphocytes, highlighting numerous lymphoid follicles with germinal centers. A diagnosis of MNC was made. We also report comparatively analyzed genetic alterations in MNC and its benign counterpart, micronodular thymoma with lymphoid stroma (MNT) by next-generation sequencing. For therapeutic interventions, awareness of this rare disease is essential in order not to confuse this tumor with MNT or metastatic carcinoma in mediastinal lymph nodes. And further clinical concordance studies with genomic analysis in the larger number of MNCs should be followed.

BackgroundIndolent NK-cell lymphoproliferative disorder of the gastrointestinal tract (iNKLPD) is a newly recognized entity in the 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid Tumours: Lymphoid Neoplasms. Initially described as "NK-cell enteropathy" and "lymphomatoid gastropathy" over a decade ago, recent molecular and cytogenetic studies have confirmed its neoplastic nature. Although primarily affecting the gastrointestinal tract, iNKLPD has also been reported in rare extra-intestinal sites, including the gallbladder, lymph nodes, nasopharynx, and vagina.Patient PresentationWe report the first documented nasal cavity lesion, identifying this anatomic site as a novel manifestation of the disease. A 67-year-old woman patient presented with recurrent postnasal drip symptoms persisting for one year following an upper respiratory tract infection. Imaging studies revealed a nasal mass on head computed tomography (CT), prompting endoscopic resection. Intraoperatively, a mulberry-like neoplasm was identified in the left nasal septum. Histopathological examination using hematoxylin-eosin (HE) staining revealed diffuse infiltration by medium to large round cells. Immunohistochemical profiling demonstrated positive expression of CD56, CD3, BCL2, TIA1, and granzyme B, with a Ki-67 proliferation index of 50%. CD5, CD20, CD21, CD23, CD10, BCL6, CD30, PAX5, and PD-1 were negative. Notably, in situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was negative, and T-cell receptor (TCR) gene rearrangement was not detected by polymerase chain reaction (PCR) analysis, confirming the diagnosis of iNKLPD. After 11 months of follow-up, the patient showed no local recurrence or signs of lymph node enlargement in other anatomical regions. Furthermore, proteomics analysis of the tumor was conducted in conjunction with gene ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.ConclusionAlthough iNKLPD is a rare tumor, lesions involving the nasal cavity are exceptionally uncommon and have not been reported in the literature. This unique lesion represents the first documented occurrence of iNKLPD in the nasal cavity, contributing to the comprehensive understanding of its pathological diagnosis and clinical management. Proteomics analysis of the tumor has provided valuable insights into the molecular mechanisms underlying this rare disease.

Microsecretory adenocarcinoma is a recently recognized low-grade salivary gland malignancy characterized by distinct histomorphological features, a specific immunophenotype, and recurrent MEF2C::SS18 gene fusion. This report describes 43-year-old woman with a two-decade history of a right buccal mucosa mass that exhibited recent enlargement, causing functional impairment. Surgical excision revealed a well-demarcated tumor with microcystic and tubular architecture, basophilic luminal secretions, and low proliferative activity (<1 mitotic figure/2mm²). Immunohistochemistry demonstrated positivity for S-100, SOX10, keratin 7, and p63, with negativity for p40, while fluorescence in situ hybridization confirmed SS18 rearrangement. No adjuvant therapy was administered, and the patient remained recurrence-free during a 3-year follow-up. This tumor confirms the slow-growing nature of microsecretory adenocarcinoma, emphasizes the importance of molecular testing for diagnosis, and clarifies the diagnostic differences between microsecretory adenocarcinoma and similar-looking salivary gland tumors.

Heavy chain diseases comprise a rare heterogeneous group of B-cell lymphoproliferative disorders characterized by the production of a truncated monoclonal immunoglobulin heavy chain without an associated immunoglobulin light chain. Gamma heavy chain disease often resembles lymphoplasmacytic lymphoma clinically and histopathologically. Its diagnosis requires the demonstration of monoclonal heavy chains in the serum or urine. We present the clinical and pathologic history of a 69-year-old woman who was incidentally identified with a monotypic B-cell population during routine flow cytometry for her untreated T-cell large granular lymphocytic leukemia. Further workup was consistent with a diagnosis of gamma heavy chain disease.