Fine needle aspiration cytologic diagnosis of erythema nodosum leprosum: a case report

BACKGROUND: Erythema nodosum leprosum (ENL), the type 2 lepra reaction occurring in lepromatous or borderline lepromatous leprosy, presents clinically with acute manifestations that compel the patient to seek medical attention. Recognition and timely management of these patients is critical in order to avoid permanent disability. Fine needle aspiration cytology (FNAC) is a simple, effective tool that aids in correct diagnosis and management of ENL. CASE: A 30-year-old woman presented with history of fever, reddening of the face, and multiple raised, reddish, painful swellings of the bilateral forearms and legs for 7 days. One year previously, she was diagnosed and treated for lepromatous leprosy with type 2 reaction. After a thorough clinical examination a diagnosis of ENL was made. FNA smears from the forearm swellings showed pus-like material with intact and degenerated polymorphonuclear leukocytes and many foamy macrophages with strong granular acid-fast bacillus (AFB) positivity. A cytologic diagnosis of ENL was given, which was confirmed on histopathologic examination of skin biopsy. CONCLUSION: Cytologic features such as a large number of intact and degenerated neutrophils with foamy macrophages and strong granular AFB positivity, in an appropriate clinical background, allows a confident diagnosis of ENL.