ABSTRACT
OBJECTIVES: The diagnosis of cutaneous tuberculosis is challenging due to its diverse clinical manifestations, paucibacillary state and lack of proper diagnostic tests. Clinico-pathological correlation is still frequently used for diagnosis. There is paucity of literature on cytomorphological features. Immunochemistry can help as an ancillary test. METHODS: Clinical diagnosis was made after thorough history and physical examination. Modified Fine Needle Aspiration technique was used to collect cytology samples and 3 mm punch biopsy for histological examination. Findings on histopathology were compared with cytomorphology. Immunochemical staining with anti-TB polyclonal antibody using standard Polymer-based-HRP immunochemistry technique and comparison of cytology and histology findings. RESULTS: The morphological spectrum of biopsy and cytology showed high correlation using nine parameters: necrosis, granulomas, giant cells, AFB, neutrophilic infiltrate, presence of lymphocytes, histiocytes, collagen bundles, and immunochemistry. Diagnostic correlation of FNA compared to biopsy was found to be 90.3%. On comparing cytomorphology of scrofuloderma and lupus vulgaris, all the parameters were found more frequently in scrofuloderma except for granulomas, giant cells and immunochemistry. Immunochemistry showed sensitivity and specificity of 90.3% and 70% on biopsy, respectively, compared to 67.7% and 60% on FNA, respectively. Combined sensitivity of IHC and ICC was 96.8%. CONCLUSIONS: The cytomorphological spectrum of cutaneous tuberculosis is comparable to clinicohistopathology with a high correlation of 90.3%. However, sub classification on FNA is difficult on cytology alone. While FNAC is a better diagnostic tool for finding AFBs hence confirming the diagnosis, biopsy is better for immunochemistry. Thus, biopsy and FNA complement each other.
