Unusual endophytic non-enhancing tumour in the renal pelvis: a diagnostic dilemma

Renal cell cancer (RCC) is incidentally detected on imaging in 50%–60% of cases. Among the RCCs, clear cell variant is most common and classically seen as heterogenous enhancing lesion on CT imaging. Hypoenhancing mass presents a diagnostic dilemma with differential diagnosis being urothelial carcinoma, fat poor angiomyolipoma, oncocytoma or rarer variants of RCC. Such cases require further evaluation in form of urine cytology or newer molecular diagnostic techniques. Here, we present a case of renal mass with minimal enhancement on CT scan and imaging features suggestive of upper tract urothelial cancer. Final histopathology revealed the mass to be chromophobe variant of renal cell carcinoma.

Primary clear cell carcinoma of gallbladder arising in porcelain gallbladder

Gallbladder carcinomas (GBCs) are the most common carcinomas of the biliary tract. The clear cell variant is encountered rarely, accounting for approximately 1% of all GBCs.Due to its rarity, the exact incidence and pathogenesis of this variant are unknown. Though hyalinising cholecystitis (porcelain gallbladder) is an established risk factor for development of conventional adenocarcinomas of the gallbladder, its role in the pathogenesis of the rare variants of GBC is not well-established. The current case raises the possibility that clear cell carcinoma of the gallbladder may arise through the same pathways as conventional adenocarcinomas of the gallbladder.

Clear Cell Odontogenic Carcinoma of the Mandible Harboring EWSR1 Rearrangement: Report of a Massive Jaw Tumor and Review of Diagnostic Considerations

Clear cell odontogenic carcinoma (CCOC) is a low-grade malignant neoplasm that affects the jaws. We report an 18 cm massive case of mandibular CCOC in a 43-year-old female. The tumor was composed of nests and cords of round to polygonal monomorphic clear cells separated by prominent stromal hyalinization. Immunohistochemically, the tumor cells showed focal cytokeratin 5/6 positivity and intracytoplasmic PAS-positive granules and were negative for S100 and after diastase treatment (PAS-D). Molecularly, this case was positive for EWSR1 rearrangement by FISH. The following should be included in the histopathological differential diagnosis: hyalinizing clear cell carcinoma of the salivary gland, clear cell variant of central mucoepidermoid carcinoma, clear cell variant of calcifying epithelial odontogenic tumor, and metastatic renal cell carcinoma. CCOC is a rare entity, with only 79 cases reported in the mandible. This case highlights the propensity for CCOC to exhibit invasiveness, destructive nature, and facial disfigurement if left untreated.