Fine-needle aspiration cytology of histoid leprosy of nipple

Sir,

Histoid leprosy is considered to be a form of lepromatous leprosy and exhibits characteristic clinical and histological features.[12] Patients usually present with nodular lesions over the dorsum of hand, arms, lower back, chest, and buttocks. Diagnosis is usually confirmed on histological examination. Fine-needle aspiration cytology (FNAC) can be a rapid, safe, and effective alternative for diagnosis in a suspected case of leprosy and only a few studies have described this entity.[2345] We report the cytomorphological findings that helped us to establish the diagnosis of histoid leprosy in a patient with nipple enlargement.

A 40-year-old male patient was referred to the cytology clinic for FNAC of right nipple enlargement. On examination, the swelling of the nipple measured 1 cm in diameter. There was no overlying erythema, discoloration, or ulceration and no discharge. FNAC yielded blood mixed and particulate material. The smears were cellular and showed multiple clusters of oval to spindle shaped cells with elongated nuclei, fine chromatin and scanty to moderate cytoplasm [Figures 1a]. The background showed numerous histiocytes and lymphocytes. Figure 1b and 1c highlights the negatively stained organisms as singly scatlered or as bundles. The modified Ziehl-Neelson (Z-N) stain for Mycobacterium leprae was strongly positive, with a bacillary index of +6 [Figure 2]. A final diagnosis of histioid leprosy was made on the basis of these clinical and cytomorphological findings.

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Figure 1

(a) Discrete spindle cells and foamy histiocytes with unstained acid-fast bacilli highlighted as negative staining (May Grunwald Geimsa stain, ×high power), (b and c) Negatively stained organisms as single or narrow bundles (arrows) and thicker bundles (arrow heads)

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Figure 2

Abundant discrete and small bunches of acid fast lepra bacilli (Modified Ziehl–Neelson stain, ×Oil immersion)

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Histioid leprosy is a distinct form of leprosy characterized by nodular tumor like swelling of the subcutaneous tissue in apparently normal skin. The nodule is usually seen in arms, buttocks, thighs and over the knees. On histology section, the lesion shows many spindle shaped cells and foamy macrophages. Lepra stain shows a bunch of acid fast bacilli within the histiocytes and also extracellularly.

Fine-needle aspiration cytology of histoid leprosy have been described by occasional studies.[235] Mehdi et al.[3] described that spindle shaped histiocytes forming whorl like arrangement along with many foamy cells are characteristic of histoid leprosy in FNAC smear. We also noted similar features in FNAC. There were many discrete spindle cells in the FNAC smear along with foamy macrophages. In addition, many rods like negative shadows were also noted. The negative images of the bunch of bacilli raised our suspicion of an infective etiology. Modified Z-N stain confirmed the diagnosis of leprosy [Figures 1b and 1c]. Without proper history, these spindle shaped cells may be mistaken as spindle cell lesions of soft tissue.[3]

In brief, FNAC can be an excellent alternative to conventional skin biopsy for the diagnosis of histoid leprosy. It is safe, less invasive, rapid, and inexpensive and permits simultaneous sampling of multiple sites, thereby improving the overall diagnostic accuracy.

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