The role of fine-needle aspiration cytology and Ziehl Neelsen staining in the diagnosis of cutaneous tuberculosis.

The present study highlights the role of fine-needle aspiration cytology (FNAC) and Ziehl Neelsen (ZN) staining in diagnosis of cutaneous tuberculosis and correlates the cytomorphological features with histopathology.FNAC and biopsy was performed on 30 cases of cutaneous tuberculosis and along with the routine stains, ZN and periodic acid Schiffs staining was carried out in all cases. On cytology, out of 9 cases of lupus vulgaris, 89% showed cohesive epithelioid cell granulomas with or without chronic inflammatory infiltrate; however, acid fast bacilli (AFB) could be demonstrated only in 22.2% on cytology while none on histopathology. Of 19 cases diagnosed as Scrofuloderma, 79% showed caseation necrosis with or without granulomas, 10.5% revealed granulomas with acute inflammatory infiltrates. AFB was demonstrated in 78.9% cases on cytology when compared with 15.8% on histopathology. No conclusion could be drawn in one case each of TBVC and lichen scrofulosorum.Hence, correlating cytomorphological patterns with clinical presentations often yields diagnostic information in cases of cutaneous tuberculosis and frequently obviates the need for biopsy especially in cases of scrofuloderma.