Papillary structures lined by abundant clear cells are seen. Psammoma bodies may be abundant in these tumors.
Nested and alveolar architecture may also be seen.
A different case again shows a papillary architecture lined by clear cells.
High power shows voluminous clear cytoplasm with prominent cell borders. There is some variation in nuclear size and shape with hyperchromasia.
Here is yet another case from a 32 year old. A different morphology can be appreciated. The neoplastic cells are seen lining these broad curvilinear branching spaces, as well as aggregating within hyalinized stroma.
High power reveals pleomorphic clear cells in irregular clusters embedded in a hyaline stroma.
Renal cell carcinomas that exhibit translocations involving chromosome Xp11.2 comprise a unique subset of RCCs that predominantly affect a younger population and accounts for at least 20% of all pediatric RCCs (Fletcher). This translocation creates fusion products with the transcription factor gene TFE3 on the X chromosome.
These Xp11.2 translocation carcinomas are accepted as a distinct entity by the WHO. Various mutations have been identified, but the most common variety is t(X;1) resulting in the PRCC-TFE3 gene fusion. The t(X;17) tranlocation results in ASPSCR1-TFE3 fusion gene, also seen in alveolar soft part sarcoma -- interestingly, by electron microscopy, membrane-bound cytoplasmic granules or rhomboid crystals as in alveolar soft part sarcoma are also appreciated. Another subset are associated with a t(6;11)(p21;q12) involving the transcription factor EB (TFEB) transcription factor.
Translocations involving TFE3 and TFEB induce overexpression of these proteins which is useful as they can be specifically identified by immunohistochemistry. Nuclear labeling for TFE3 is specific to Xp11.2 translocations whereas TFEB is specific to t(6;11)(p21;q12) (Argani 2003; Argani 2005).
Grossly, these translocation RCCs appear similar to clear cell RCCs. They appear as solitary masses with tan-yellow cut surfaces along with hemorrhage and necrosis. Microscopically, a papillary architecture is most common, but nested/alveolar patterns may also be seen. Papillae are covered by abundant clear cells, although cells with more eosinophilic cytoplasm may be seen. Psammoma bodies are common features (Fletcher, Zhou). There are variations in morphology among the subtypes, but it is beyond the scope of this synopsis.
Affects children and young adults. The incidence in adults is unclear.
Since this is a rare tumor only recently recognized, prognosis is difficult to assess currently. Early studies suggest that these tumors often present at a more advanced stage, but usually have s relatively indolent course. For example, among 29 cases with followup, 68% percent were disease-free, while 1 patient had lymph node recurrence after 36 months, 1 patient had liver and lung metastases after 9 months and 1 patient developed multiple metastases after 2 years (Camparo). Five patients (16%) died (Camparo).
Argani P, Lal P, Hutchinson B, et al. Aberrant nuclear immunoreactivity for TFE3 in neoplasms with TFE3 gene fusions: a sensitive and specific immunohistochemical assay. Am J Surg Pathol. 2003;27:750–761
Argani P, Lae M, Hutchinson B, et al. Renal carcinomas with the t(6;11)(p21;q12): clinicopathologic features and demonstration of the specific alpha-TFEB gene fusion by immunohistochemistry, RT-PCR, and DNA PCR. Am J Surg Pathol. 2005;29:230–240.
Camparo P, et al. Renal translocation carcinomas: clinicopathologic, immunohistochemical, and gene expression profiling analysis of 31 cases with a review of the literature. Am J Surg Pathol. 2008 May;32(5):656-70.
Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 499.
Zhou M, Magi-Galluzzi, C. Genitourinary Pathology: Foundations in Diagnostic Pathology. Philadelphia, PA: Elvesier; 2006: 297-9.