Fine-Needle Aspiration as a Key Diagnostic Tool in Pediatric Rosai-Dorfman Disease: A Case Report of a 12-Year-Old Male.

Background: Rosai-Dorfman Disease (RDD) is a rare, benign, non-Langerhans cell histiocytosis characterized primarily by massive, painless cervical lymphadenopathy. Its low prevalence (~ 1:200,000) and clinical similarity to endemic conditions like tuberculosis and lymphoma make the diagnosis challenging, particularly in resource-limited settings. Definitive diagnosis hinges on identifying S100-positive histiocytes exhibiting the pathognomonic feature of emperipolesis. Case Presentation: A previously healthy 12-year-old male from Uganda presented with a one-month history of progressive, asymptomatic, bilateral cervical lymphadenopathy. Systemic symptoms were absent. A provisional diagnosis of RDD was established rapidly via Fine Needle Aspiration Cytology (FNAC). Cytological smears showed abundant histiocytes demonstrating clear emperipolesis, confirming the classic cytological diagnosis. Despite the recommendation for a confirmatory excisional biopsy and further subtyping, the patient was lost to follow-up. Conclusion: This case demonstrates that high-quality FNAC can reliably establish the diagnosis of RDD in environments where advanced diagnostic tools are scarce, but also underscores the critical need to strengthen patient follow-up systems to ensure complete evaluation and long-term monitoring of rare histiocytic disorders.