Granuloma annulare and possible relation to purified protein derivative administration: a case report

Granuloma annulare is a noninfectious inflammatory granulomatous skin disease characterized by an erythematous or skin colored annulare plaque. The diagnosis of granuloma annulare may be challenging owing to its diverse morphology. In such cases, a correlation between the clinical findings and histologic findings are necessary.

We report a case of granuloma annulare after purified protein derivative administration. A 56-year-old Caucasian female patient complained of mildly pruritic rashes which started on both arms and lower extremities, and eventually spread to both thighs, the left popliteal region, left upper back, and the right abdominal area. About 6 weeks prior to the eruption of the rashes, the patient had been given a purified protein derivative tuberculin skin test. Biopsy specimens revealed dermal histiocytes palisading around areas of mucin and degenerated collagen, confirming granuloma annulare. After treatment with 0.1% topical triamcinolone acetanide and 500 mg oral metronidazole, the patient's lesions resolved.

Relatively little is known about granuloma annulare's exact etiology. Granuloma annulare has four variations presenting as either localized, generalized, subcutaneous, or perforating and patch granuloma annulare. The clinical prognosis for granuloma annulare varies according to clinical subtypes. Proposed causal mechanisms of subcutaneous granuloma annulare include physical trauma, infections, immunizations, insect bites, diabetes mellitus, and alterations in the cell-mediated immune responses. The disease likely has an inflammatory component. Clinically, granuloma annulare may be confused with many other skin diseases.

This case of subcutaneous granuloma annulare was reported since it is a rare dermatologic pathological condition that can be confused with other skin rash disorders. Although it is a benign self-limited disease, definitive diagnosis is important to rule out other pathologies with similar clinical appearances, such as cancer or human immunodeficiency virus (HIV) infection. Diagnostic confirmation is best made through skin biopsy.