Cytological diagnosis of Xp11 translocation renal cell carcinoma: An unusual suspect in bone metastases from unknown primary malignancies

Abstract

Background Renal cell carcinoma (RCC) constitutes 3% of all cancers, with a higher incidence in patients with age between 60 and 70 years. RCC frequently present as a metastatic tumor at diagnosis, and bones represent one of the most frequent sites. Many cases, mainly in young patients, includes the Xp11 translocation RCC. The cytological diagnosis of Xp11 translocation RCC in adult population it is rarely performed, likely for the morphological overlap with other adult renal cell carcinoma subtypes. Methods We retrospectively analyze a series of 92 adult patients with metastatic bone tumors, diagnosed on fine‐needle aspiration cytology (FNAC) samples, focusing mainly on the cytological, immunophenotypic and molecular features of Xp11 translocation RCC. Results In our series 6 of 92 (6.5%) cases were metastatic RCC (mRCC), among them 2 cases were metastasis from Xp11translocation RCC. Those cases showed a bloody background, with several groups of atypical cells arranged in syncytial groups or in papillary groups composed by atypical cells with abundant cytoplasm, with scattered clear cells. TFE3 was positive on immunocytochemical analysis and specific translocation t(Xp11.23) was detected by FISH analysis. Conclusions In adult patients with mRCC, it is necessary to consider also Xp11 translocation RCC among the diagnostic hypotheses. FNAC represents a valid tool to investigate bone lesions but cytological features of Xp11 translocation RCC are still poorly described and must necessarily be better defined.

Unravelling the mysteries of Xp11.2 translocation‐associated renal cell carcinoma: A case report with a review of the literature

“…Most Xp11.2 TRCC cases are detected in the early stages; however, some patients may have metastasis at presentation. Lungs, lymph nodes, and bones are the common metastatic sites for these tumours 8,17 …”

“…The cytological features of Xp11.2 TRCC have been documented sporadically in the literature in different cytological samples, including urine smears, effusion smears, imprint smears, and FNAs 11–13,17,20–28 . The FNA smears are usually cellular, with the tumour cells arranged in papillae and scattered singly.…”

“…The treatment for Xp11.2 TRCC is not yet standardised, and most institutions follow the same treatment protocol as for conventional RCCs. Total or partial nephrectomy remains the standard surgical treatment depending on the stage of the disease, along with immunotherapy and molecular targeted therapies 17 . Targeted therapies against vascular endothelial growth factor and mammalian target of rapamycin (mTOR) have shown some beneficial effects in Xp11.2 TRCCs.…”

“…Lungs, lymph nodes, and bones are the common metastatic sites for these tumours. 8,17 Radiologically, Xp11.2 TRCC is mainly seen as a well-defined, hypoechoic, and highly vascular lesion with foci of calcification.…”

“…14 The cytological features of Xp11.2 TRCC have been documented sporadically in the literature in different cytological samples, including urine smears, effusion smears, imprint smears, and FNAs. [11][12][13]17,[20][21][22][23][24][25][26][27][28] The FNA smears are usually cellular, with the tumour cells arranged in papillae and scattered singly. The tumour cells are round to polygonal in shape and show moderate pleomorphism with large round nuclei, finely granular chromatin, conspicuous nucleoli, and moderate to abundant amount of granular eosinophilic to pale vacuolated cytoplasm.…”