A Curious Case of Clear Cell Morphology in a Patient with Lung Cancer: Diagnostic Challenges.

An 82-year-old woman with COPD presented to the emergency department with cough, increasing sputum production, wheezing, and worsening shortness of breath for two weeks. On imaging studies, the patient was found to have a right upper lobe spiculated nodule and an endobronchial lesion with near total occlusion of the right lower lobe bronchus with sub-segmental atelectasis. Bronchoscopy with EBUS-TBNA of subcarinal and right hilar lymph nodes revealed lung cancer with clear cell phenotype. Given the predominance of clear cell morphology, the diagnosis of metastatic renal or ovarian cancer was entertained. However, there was no evidence of renal or ovarian lesions on the PET-CT scan, ruling out the possibility. Salivary gland type lung cancer (STLC), which is responsible for less than 1% of all lung cancer cases in adults, was also considered. The two distinct STLCs that may have similar morphologic appearances are hyalinizing clear cell carcinoma (HCCC) and mucoepidermoid carcinoma (MEC). The other type of tumour in the lung that demonstrates a clear cell phenotype is perivascular epithelioid cell neoplasms or PEComa, which are mesenchymal in origin. Immunohistochemical staining was strongly positive for p63, CK5/6, CK7, CK-LMW, and negative for TTF-1, Napsin A, p16, and CK20. Additional staining, including HMB-45, S-100, and mucicarmine, were also negative. Next-generation sequencing for the salivary gland fusion panel, including EWSR1-ATF1 fusion and EWSR1 gene rearrangement for HCCC and MAML2 gene rearrangements for MEC, was negative. She was diagnosed with non-small cell lung cancer favouring squamous cell carcinoma with clear cell phenotype, a rare entity.

Analyses of molecular and histopathologic features and expression of PRAME by immunohistochemistry in mucosal melanomas.

Mucosal melanomas are rare, and less is known about the biomarkers of this subtype in comparison to cutaneous or uveal melanomas. Preferentially expressed antigen in melanoma (PRAME) has been studied as a tool for prognostication of uveal melanomas, and immunotherapy against PRAME-expressing tumor cells has already shown promise. Our goal was to retrospectively analyze 29 cases of mucosal melanomas at our institution to determine if any molecular and histopathologic prognosticators could be identified, as well as to study PRAME expression and its association with prognosis. We found that the majority of mucosal melanomas expressed PRAME and a high PRAME expression score predicted a poor prognosis. There was no association between prognosis and the histomorphologic features analyzed, such as presence of spindle cell or epithelioid predominance. BRAF mutations were absent in 16 of 16 cases tested. Pathogenic NRAS mutations were detected in 3 of 11 cases tested and were associated with shorter overall survival compared to those without NRAS alterations, but the presence of NRAS mutations did not correlate with PRAME expression. In conclusion, an increase in PRAME expression and the presence of a pathogenic NRAS were both associated with a worse prognosis in mucosal melanomas.

Tackling the Diagnosis: Solid Pseudopapillary Tumor of the Pancreas in a Young Man.

Solid pseudopapillary tumor (SPT) of the pancreas is an extremely rare pancreatic tumor. It usually goes undetectable for a prolonged period of time given its lack of clinical symptoms. But when detected, it has a malignancy potential of 15%. Here we present a case of SPT diagnosed incidentally in a 17-year-old man during a routine evaluation for an abdominal trauma.

Cytomorphologic features of malignant solitary fibrous tumor with mediastinal involvement sampled by endoscopic and endobronchial ultrasound-guided fine-needle aspiration: A comparison of two cases.

Solitary fibrous tumor (SFT) is an uncommon fibroblastic neoplasm with considerable risk of local recurrence. SFT is histologically characterized by bland spindled-to-epithelioid cells in alternating hyper- and hypocellular zones, a "patternless pattern," ectatic "staghorn" vessels with variable edematous perivascular stroma, and thick ropey collagen. Cytologically, smears are variably cellular with spindled-to-epithelioid cells with oval nuclei, wispy cytoplasm, multiple inconspicuous nucleoli, and occasional nuclear pseudoinclusions. Small vessels and bare/stripped nuclei are generally present while mild atypia is not uncommon. STAT6 nuclear expression is the most useful immunohistochemical stain and is the product of a NAB2-STAT6 gene fusion. SFTs with mediastinal involvement may be diagnostically challenging due to proximity to vital structures and anticipated patient risks. Endobronchial and endoscopic ultrasound-guided fine-needle aspiration (EBUS/EUS-FNA) are minimally-invasive tissue sampling methods that provide diagnostic material while minimizing patient risk, and the mediastinum is accessible by both procedures. Small aspirate samples and SFT nonspecific features can compound the diagnostic difficulty, although familiarity with the cytologic, morphologic, immunophenotypic, and genetic features of SFTs assist the pathologist in confirming the diagnosis. Pathologists must also be aware of high-risk SFT features to ensure appropriate therapy and management. Case #1 describes a recurrent mediastinal SFT with high-risk features sampled by EUS-FNA. Case #2 describes a primary diagnosis of mediastinal SFT with malignant behavior made on an EBUS-FNA specimen.

Isolated Large Cell Calcifying Sertoli Cell Tumor in a Young Boy, not Associated with Peutz-Jeghers Syndrome or Carney Complex.

BACKGROUND: Large cell calcifying sertoli cell tumor (LCCSCT) is an exceedingly rare lesion of the testicle. It is most often seen in patients with Carney complex (CNC) or Peutz-Jeghers syndrome (PJS). We now report the first pediatric patient with what appears to be bilateral LCCSCT and no other conditions or a genetic syndrome, such as PJS or CNC, have been associated with it. METHODS: A 10-year-old boy was found to have a right testicular mass during a routine pediatric examination; he underwent right orchiectomy. He was then evaluated clinically for PJS or CNC and underwent genetic testing. His tumor was studied by immunohistochemistry for the expression of calretinin, NY-ESO-1, inhibin, CD99, S100, PLAP, AE1/AE3, Bcl-2, p53, and Mib1. RESULTS: Patient did not have clinical features or genetic abnormalities of CNC and PJS. Microscopic features showed large, round or cubical intratubular and aggregated tumor cells with prominent nuclear atypia, large and prominent nucleoli and extensive calcification. In the Immunohistochemical studies, calretinin and inhibin alpha were up regulated in LCCSCT as compared to the adjacent benign Sertoli cells. Meanwhile, NY-ESO-1 and CD99 were down-regulated in LCCSCT. Focally and weakly positive S100 was found in the tumor tissue, but no S100 expression was present in the adjacent Sertoli cells. There was no expression of PLAP, P53, Bcl-2, Mib1 and AE1/AE3 in LCCSCT and adjacent Sertoli cells. Micro-calcifications were found in the other gonad by ultrasonography, suggesting LCCSCT. CONCLUSION: LCCSCT is a rare testicular neoplasm, and may present in isolated rather than in more typical association with syndromes such as CNC and PJS.