An 8-year-old female child presented with asymptomatic reddish skin lesions over the dorsum of her right foot for six months. There was no history of trauma. Family history was not contributory. Dermatological examination revealed an annular erythematous plaque of size 5 × 4 cm with a central clear area and minimal scaling along with a few erythematous papules and plaques in the close vicinity, involving the lateral aspect of dorsum of right foot [Figure 1]. On diascopy, apple jelly nodules were seen. Sensations were intact. No cutaneous nerve twigs were palpable, entering or leaving the plaque and peripheral nerves were normal. There was no regional adenopathy. Hair, nail, and mucous membranes were normal. Systemic examination did not reveal any abnormality.
Figure 1.
Annular erythematous plaque with minimal scaling along with few erythematous plaques over the dorsum of right foot
Routine hematological and biochemical investigations were within normal limits. KOH mount for fungus was negative. Chest radiography was normal. Mantoux test showed an induration measuring 11 mm. Histopathology revealed dermis showing granulomas composed of epithelioid cells, lymphocytes, foreign body, and Langhans giant cells, a picture compatible with lupus vulgaris (LV) [Figures 2 and 3]. A diagnosis of LV was entertained and the patient was treated with category one antitubercular therapy with significant resolution of lesions by the end of the intensive phase of therapy.
Figure 2.
Dermis showing diffuse granulomas (H and E, ×100)
Figure 3.
Granulomas composed of epithelioid cells, lymphocytes, and Langhans giant cells (H and E, ×400)
LV is the most common type of cutaneous tuberculosis that tends to affect the lower half of the body involving legs, thighs, buttocks, and feet and is attributed to the habit of children playing without clothing or shoes and defaecating in the open.[1]
Among the frequent morphological variants such as plaque, hypertrophic, papulonodular, ulcerating, and vegetating forms, the common type is the plaque form that presents as flat plaques with irregular or serpigenous edges, surface may be smooth or covered with a psoriasiform scale,[2] as in our case, but in an annular fashion.
Atypical forms of LV described include sporotrichoid, annular, psoriasiform, mimicking a port wine stain, manifesting as alopecia, simulating mycetoma, discoid lupus erythematosus, and lichen simplex chronicus.[3] This case is highlighted for the rare annular morphology of LV.
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REFERENCES
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