The Curious Case of an Elusive Solitary Plaque

Abstract

A 60-year-old male patient presented with a solitary pink plaque over the inner aspect of the left forearm of 4 years duration. The lesion was persistent and unresponsive to treatment. A skin biopsy was done with differential diagnosis of lupus vulgaris, tuberculoid leprosy, and granuloma annulare. Histopathology revealed features suggestive of morphea and the patient was treated accordingly. Despite treatment, the lesion continued to grow in size and a repeat biopsy was done as clinical doubt regarding the diagnosis persisted. Dermoscopy, KOH wet mount, and histopathology revealed characteristic features that clinched the diagnosis and aided in correct management of the patient with complete clearance of lesion after 4 months of therapy.

Keywords: Dermoscopy; histopathology; solitary plaque.

Figure 1

(a): Multiple erythematous papules coalescing to form a plaque with central clearing in an annular pattern on the flexor aspect of the left forearm. (b): Flattening of the rete ridges, sparse superficial and deep lymphohistiocytic infiltrate and reticular collagen thinned at places, arranged parallel to the surface epidermis suggestive of morphea (H and E 100×)

Figure 2

(a): Erythematous to violaceous papules and nodules studded with brown to black hemorrhagic crusts and scaling. (b): Dermoscopy revealed a pink and white background with a white net-like pattern with polymorphous blood vessels, multiple red-brown to black dots, scaling and crusting (DermLite DL4, 10×, Polarized mode). (c): KOH wet mount of the overlying crusts show multiple brown colored, septate medlar bodies. (d): Cluster of thick-walled refractile yeast cells, “Cluster of pennies appearance” seen on repeat biopsy (H and E 400×)

Figure 3

Complete regression of the lesion after 4 months of treatment