Abstract:

In its earliest stages, the histology of morphea may show interstitial histiocytic infiltrate, resembling that of interstitial granulomatous dermatitis (IGD). While this similarity has been documented in some texts, few cases have been reported. We present a case that initially showed histologic features presented as IGD, but developed features more classic for morphea, upon a follow-up biopsy. The patient was a 13-year-old male who presented with violaceous lesions on the abdomen, chest, upper thighs, and upper left arm. The first punch biopsy of the left upper abdomen revealed a perivascular and interstitial pattern with interstitial histiocytes mixed with rare plasma cells, favoring IGD. Two months later, a second punch biopsy of the left posterior thigh revealed dermal sclerosis associated with a decreased CD34 immunostain in the dermis, as well as superficial and deep perivascular and interstitial mixed infiltrate of lymphocytes, histiocytes and rare plasma cells. These findings were most compatible with morphea. IGD is characterized by erythematous and violaceous patches and plaques over the lateral trunk, buttocks, and thighs. Morphea lesions are characterized as slowly developing and manifesting as erythema during its onset, densely sclerotic, and containing a violaceous border. Lesions of morphea commonly occur on the chest and neck, the lower extremities, the upper extremities, and the face. We review some of the prior literature on IGD as the initial presentation of morphea, and detail the histological clues that can be used to arrive at the correct diagnosis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Peter Mikhlin