Hyaline Vascular Type of Castleman Disease: Diagnostic Pitfalls on Cytology and Its Clinical Relevance.

Castleman disease (CD) is an uncommon cause of lymphadenopathy. The role of fine-needle aspiration cytology (FNAC) as a diagnostic modality in this disease is not well established. Cytological features of CD have a considerable overlap with many reactive conditions. It has subtle morphological features; which if overlooked, may miss the diagnosis. A two-year-old girl presented with cervical lymphadenopathy. FNAC of the cervical lymph node showed features of granulomatous lymphadenitis. Excision biopsy revealed the hyaline vascular type of CD. Cytological smears were reviewed carefully and revealed indicators of CD. These included capillary fragments with adherent reactive lymphoid cells, plump endothelial cells and pale pink material admixed with germinal center cells. The collections of plump endothelial cells had been misinterpreted as granulomas previously. This report highlights the subtle cytomorphological pointers of CD. Careful scrutiny for these features could aid the cytologist in differentiating CD from other reactive and neoplastic disorders, thus avoiding cytodiagnostic pitfalls. This case study reiterates an important fact that for a lymph node lesion, histopathology plays a crucial role in differentiating mimickers and renders an accurate diagnosis.