HISTOID RELAPSE IN LEPROMATOUS LEPROSY

Dear Editor.

We would like to report a rare variety of lepromatous leprosy called ‘Histoid leprosy’ which has become uncommon in the era of multidrug therapy. Wade [1] in 1963 first time described skin lesions of lepromatous leprosy resembling a tumour which histopalhologically showed well circumscribed tumorous collection of spindle shaped histiocytes in deep dermis and abundance of acid fast bacilli. The lesions are classically firm and succulent cutaneous nodules on apparently normal skin. This may appear de novo [2] or as a relapse case of lepromatous leprosy [3].

The present case was a 55-year-old ex-serviceman who was diagnosed as lepromatous leprosy in 1971. Old documents revealed that he had bilaterally symmetrical multiple hypopigmented lesions all over body with infiltration over face and ear lobules and glove and stocking type of sensory loss. All peripheral nerves were thickened but nontender. Bacterial Index was 6+. He was treated with dapsone mono-therapy and became bacteriologically negative after 5 years with regression of lesions and nerve thickening. In October 96 he came for review with complaints of spontaneous appearance of nodular lesions on back and extremities of 2 months duration. No abnormality was detected on general and systemic examination.

Dermatological examination revealed multiple, painless, smooth, shiny, succulent nodules of 0.5 to 2 cm size on lower back, both arms and thighs. There was no infiltration of face or fresh hypopigmented lesion and no peripheral nerve thickening. During hospitalisation he also developed herpes zoster. Routine haematological investigation, urinalysis, LFT and blood sugar were normal. Slit skin smear showed AFB (L) from nodules. ELISA for HIV – 1/2 were non-reactor. The CD₄+T cell count was 655/cmm and absolute lymphocyte count was 1140/cmm. Skin biopsy from nodule showed collection of band of spindle shaped cells alongwith foamy macrophages and acid fast bacilli (Fig 1). Patient was put on WHO recommended multidrug therapy for multibacillary leprosy. He responded well to therapy and lesions regressed satisfactorily in next one year.

Fig. 1.

a) Multiple spindle shaped cells in dermis × 10.

b) Multiple spindle shaped cells with foamy appearance in dermis × 40.

Before the introduction of multidrug therapy by WHO in 1982 [4] the relapse rate of multibacillary leprosy was reported to be as high as 19 per cent. This was mostly due to dapsone resistance [5]. The relapse rate has now come down to as low as 0.74 per cent in multi-bacillary cases following use of multidrug therapy [6]. The cause of relapse of leprosy after almost 20 years of bacterial negativity in our case is not clear. However, generalised immune depression due to old age as seen by low CD₄+T cell count and low absolute lymphocyte count might have resulted in reactivation of leprosy as well as herpes zoster. The aim of reporting this case is mainly to highlight the importance of regular check up of leprosy patients so that such cases could be identified early and treated adequately with multidrug therapy.