Sporotrichoid lupus vulgaris: A rare presentation.

Lupus vulgaris is the most common presentation of cutaneous tuberculosis in India and can present as papular, nodular, plaque, ulcerative, vegetating, and tumid forms. Unusual variants include the frambesiform, gangrenous, ulcerovegetating, lichen simplex chronicus, myxomatous, and sporotrichoid types. We describe a rare sporotrichoid presentation of lupus vulgaris on the leg of a 28-year-old female of 12 years duration.

INTRODUCTION

Cutaneous tuberculosis (TB) forms a small proportion of extrapulmonary TB.[1] Studies from India report an incidence of cutaneous TB of 0.1%.[23] Lupus vulgaris is the most common morphological presentation of cutaneous TB that can present as papular, nodular, plaque, ulcerative, vegetating, and tumid forms. It often originates from an underlying focus of TB, typically in a bone, joint or lymph node, and spreads by either contiguous extension of the disease from underlying affected tissue, or by hematogenous or lymphatic spread. It may also occur after exogenous inoculation,[4] or Bacillus Calmette–Guérin vaccination.[5] It is a paucibacillary type of cutaneous TB and occurs in a patient of a moderate immunity. A typical feature of lupus vulgaris is its extremely chronic course, characterized by a slow and steady growth of the lesion over a period of years. Unusual variants include the frambesiform, gangrenous, ulcerovegetating, lichen simplex chronicus, myxomatous, and sporotrichoid types.[6] Herein we report a rare sporotrichoid presentation of the disease.

CASE REPORT

A 28-year-old female with family history of TB presented with multiple, asymptomatic, raised skin lesions of variable size and shape over her right lower limb. Lesions first appeared on the upper surface of her right foot 12 years ago [Figure 1] after a thorn prick. Thereafter, they extended steadily upward to her inner thigh, increasing both in number and size. There was a history of scarring at one end of the lesions and extension from the other. Examination of the right lower limb revealed polysized plaques of 4-8 cm diameter with central scarring and peripheral nodularity extending in a linear array from the dorsum of the lateral three toes to the medial aspect of ankle joint, knee joint, and medial aspect of the upper thigh in a sporotrichoid pattern [Figure 2]. The lesion on the dorsum of the foot was also ulcerated. There was matted unilateral inguinal and cervical lymphadenopathy. Hematological investigations are within normal limits. Serology for human immunodeficiency virus was nonreactive. Chest radiograph posteroanterior view and radiograph of the right foot were normal. Mantoux test showed 16 mm induration. Histopathology revealed hyperkeratosis, acanthosis and elongation of the rete ridges with dense dermal granulomas comprising epithelioid cells, Langhan's type giant cells and chronic inflammatory cells, supporting a diagnosis of lupus vulgaris [Figure 3].

Figure 1

Plaque from dorsum of the foot in a sporotrichoid pattern

Figure 2

Plaque in sporotrichoid pattern

Figure 3

Histopathology showing granulomas comprising epitheloid cells and Langhan's type giant cells (H and E Stain, ×40)

A final diagnosis of sporotrichoid-lupus vulgaris was made and the patient referred to the government TB clinic for category I DOTS.

DISCUSSION

Sporotrichoid form of lupus vulgaris is an unusual variant[7] that mimics sporotrichosis, a subcutaneous fungal disease.[8] Bacilli follow the lymphatic channels and during transit, provoke cutaneous granulomatous inflammation resulting in a linear array of papular, nodular and ulcerative lesions over time. It has been shown that sporotrichoid form is more common in children than in adults. The efficient lymphatic drainage in children and high physical activity that makes them prone to trauma may be responsible for this form.[6] As it is a complex process and takes time, this presentation of lupus vulgaris is rare.