Differential diagnosis and unusual diffuse cytokeratin expression in renal paraganglioma: A case report

Paraganglioma is a rare neuroendocrine tumor arising from undifferentiated cells of the primitive neural crest. We report a case of renal paraganglioma in a 67-year-old patient. Computed tomography demonstrated a solid mass in the middle and lower pole of the right kidney. Sonography revealed an enlarged right kidney with an irregular shape but distinct border. Renal cell carcinoma was diagnosed provisionally; the tumor was completely resected and submitted for pathological examination. Unexpectedly, histopathology and immunohistochemistry confirmed paraganglioma arising from the renal parenchyma. In this study, we report the exceptional occurrence of Paired box gene 8 (PAX-8) expression in a renal paraganglioma. In addition, we demonstrated diffuse cytokeratin positivity in this renal paraganglioma. Although our report of a paraganglioma originating from the kidney is not unique, our finding expands the known immunophenotypic spectrum of this tumor. The awareness of the possible occurrence of cytokeratin diffuse positivity in paraganglioma is relevant to avoiding misdiagnosis of paraganglioma.

Primary epiglottic follicular variant of peripheral T-cell lymphoma

The follicular variant of peripheral T-cell lymphoma, not otherwise specified, is very rare. Primary epiglottic follicular variant of peripheral T-cell lymphoma is extremely rare in clinical practice. Here, we report the first case of a follicular variant of peripheral T-cell lymphoma not otherwise specified in a 44-year-old Chinese man, who presented with a tumor in the middle of the epiglottis tongue surface. Microscopically, the tumor had a vague nodular growth pattern and the morphology of the nodules was different from each other at low power. Atypical lymphoid cells were medium to large in size and had round nuclei, with an irregular nuclear membrane, distinct nucleoli, and rapid mitotic activity. Plasma cells were found surrounding the nodules. The tumor cells were positive for follicular helper T-cell markers (CD10, PD-1, CXCL13, and BCL-6). The EBER was negative by in situ hybridization. Polymerase chain reaction-based analysis showed monoclonal rearrangements of TCR?, TCR?, and polyclonal rearrangements of IgH, IgK, and IgL. The clinical and imaging features and the prognostic factors of FV PTCL-NOS remain poorly understood. Thus, investigation of more cases and longer follow-up is necessary to understand the disease and to identify the best treatment to improve prognosis.