Cytodiagnosis of erythema nodosum leprosum. A case report.

BACKGROUND

The application of cytology in leprosy has been restricted to the evaluation of morphologic and bacterial indices by slit skin smears to facilitate diagnosis of cases according to the Ridley-Jopling scale. Isolated reports have now documented the use of fine needle aspiration cytology (FNAC) in the diagnosis of leprosy.

CASE: A 45-year-old male presented with the abrupt onset of multiple nodular eruptions all over the body. The clinical diagnosis was Sweet's syndrome. FNAC showed numerous neutrophils in a background of foamy macrophages. Special stains revealed the presence of a large number of fragmented acid-fast bacilli in the smears. A diagnosis of erythema nodosum leprosum (ENL) was made on FNAC.

CONCLUSION

The presence of neutrophils in a characteristic milieu of foamy macrophages is seen in lesions of ENL. Such a picture should prompt the cytologist to use a modified Ziehl-Neelsen stain to demonstrate acid-fast bacilli, as ENL can present as an acute episode in patients without a previous diagnosis of leprosy.