Tumor-like lesions of histoid leprosy in an elderly male

A 72-year-old man consulted us in the dermatological outpatient clinic for multiple non-pruritic, skin-colored solid raised lesions that were present all over his body and had been slowly increasing in size and distribution for 2 years. There was no history of any medication intake before the appearance of these lesions and patient never took any treatment for his condition. Neither the patient nor his family members had a history of leprosy. He was otherwise healthy with stable vitals and no lymphadenopathy was detected.

Cutaneous examination revealed multiple normochromic to erythematous, dome-shaped, firm, and non-tender papules (0.2 to 0.5 cm), superficial and deep-seated nodules (1 to 1.5 cm) on normal surfaces, distributed on the neck, trunk, and all extremities (Figure 1); in addition, an umbilicated nodule on abdomen and tumor-like lesions of varying sizes (0.5 cm × 1 cm to 2 cm × 2.5 cm) were observed over the abdomen and lower back (Figure 2A,2B). The face, ears, palms, soles, and mucous membranes were spared. Sensations were intact over the lesions. Hypoesthesia was noted along the distribution of the left ulnar nerve, which was cord-like thickened, but no motor weakness was noted.

Figure 1 Multiple discrete, shiny, succulent papules arranged singly or coalescing with each other (red arrows) and skin-colored, smooth and dome-shaped nodules (black arrows) present behind the left ear, side and nape of the neck. This image is published with the patient’s consent.

Figure 2 Depicting atypical lesions of histoid leprosy in our patient located on different anatomical sites. (A) Multiple coalescent papules giving rise to a tumor-like lesion (black arrow) and a molluscum contagiosum-like umbilicated nodule over the abdomen (red arrow). (B) An erythematous, shiny, smooth tumor-like lesion of size 2 cm × 2.5 cm (black arrow) with nodular protuberances on a normal-looking skin located over lower back along with multiple surrounding papules and nodules. The images are published with the patient’s consent.

Hematologic and biochemical blood tests were within normal range and viral markers including enzyme-linked immunosorbent assay for human immunodeficiency virus were non-reactive. His chest radiographic findings were unremarkable. Histoid leprosy, cutaneous metastasis, neurofibromas and dermatofibromas were retained as differential diagnoses. Bacilloscopic examination revealed a bacillary index of 1.6. A 4-mm skin punch biopsy of a nodule demonstrated a dermal collection of spindle-shaped histiocytes arranged in a whorl and crisscross pattern on haematoxylin-eosin staining (Figure 3). Visualization of acid-fast bacilli in the Ziehl-Neelsen stain was also noted which was consistent with the diagnosis of histoid leprosy (Figure 4). As a result, multidrug therapy for multibacillary leprosy (MDT-MB) in monthly blister pack consisting of rifampicin 600 mg once monthly, clofazimine 300 mg once monthly plus 50 mg once daily and dapsone 100 mg once daily was started at a government facility free of cost near his home for a period of 2 years, and monthly follow-up visits to our institute were recommended.

Figure 3 Hematoxylin-eosin stain of biopsied tissue revealing normal looking epidermis (black arrow), subepidermal grenz zone (red arrow), and spindle-shaped histiocytes arranged in a crisscross and whorled pattern (black and red asterisks) (40× magnification).

Figure 4 Demonstration of pink-colored solid stained cylindrical bacilli with round ends, few slightly elongated bacilli with tapered ends and granular bacilli on Ziehl-Neelsen stain of histopathological section (black arrows) (100× magnification).

Histoid leprosy is a rare variant of lepromatous Hansen’s disease caused by localised loss of cell-mediated immunity to Mycobacterium leprae, resulting in the development of histoid lepromas. The age of onset is 21 to 40 years; uncommon in older age as observed in our case. Previous literature mentions that histoid leprosy occurs in patients with lepromatous leprosy in the context of dapsone monotherapy and de novo cases are rare. However, in contrast to previous studies, a more recent study observed that all cases in their data were de novo which is similar to our case. Cutaneous histoid lepromas usually present as dome-shaped, smooth, shiny, and firm cutaneous/subcutaneous nodules on normal-appearing skin that occur asymmetrically on the face, trunk, and extremities. Infiltration of the earlobes and loss of sensation over the lesions may be absent. All these features were consistent with our case.

Rarely atypical molluscum-like lesions and tumor-like lesions, as observed in our patient, may occur in histoid leprosy. The exact mechanism of development of histoid tumors is not well understood; however, the coalescence of multiple nodules has been suggested in literature. This theory was supported by the presence of multiple protuberances in the tumors clinically evident in our patient. Due to the presence of these tumor-like lesions, cutaneous metastasis had to be excluded in this case, which may have features similar to histoid leprosy, especially in elderly patients. However, bacilloscopic and histopathologic examination helped confirm the diagnosis of histoid leprosy.

Finally, for the proper implementation of leprosy eradication programmes, early detection and treatment of histoid leprosy is of paramount importance, as these cases are well-known reservoirs of the infection.

Acknowledgments

Funding: None.

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

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