Lichenoid and granulomatous dermatitis

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Abstract
Background The prototypic lichenoid eruptions, lichen planus (LP), lichenoid drug eruptions, secondary syphilis, and collagen vascular disease, are defined histologically by a band‐like lymphocytic infiltrate in close apposition to the epidermis. We describe a novel form of lichenoid dermatitis with a granulomatous component. Design Skin biopsies from 40 patients demonstrating a band‐like lymphocytic infiltrate with concomitant granulomatous inflammation were encountered over 4 years. Clinicians were contacted to elucidate underlying triggers and medical illnesses. Results A lichenoid dermatitis, a linear eruption, vasculitis, annular erythema, and erythroderma were among the clinical presentations. A drug‐based etiology was implicated in 14 cases: the drugs included antibiotics, lipid‐lowering agents, anti‐inflammatory drugs, antihistamines, hydroxychloroquine sulfate, and angiotensin‐converting enzyme inhibitors. Over one‐third of patients with drug‐related eruptions had other medical illnesses associated with cutaneous granulomatous inflammation, namely rheumatoid arthritis (RA), Crohn’s disease, hepatitis C, diabetes mellitus, and thyroiditis. A microbial trigger was implicated in 12 patients in the context of infective id reactions to herpes zoster, Epstein–Barr virus (EBV), or streptococci, or active infections by Mycobacterium tuberculosis, M. leprae, fungi, and spirochetes. The remainder had hepatobiliary disease and RA without obvious exogenous triggers, cutaneous T‐cell lymphoma (CTCL), and idiopathic lichenoid eruptions (i.e. LP, lichen nitidus, and lichen striatus). One patient with LP had underlying multicentric reticulohistiocytosis. The histiocytic infiltrate assumed one or more of five light microscopic patterns: (i) superficially disposed loose histiocytic aggregates; (ii) cohesive granulomata within zones of band‐like lymphocytic infiltration with or without deeper dermal extension; (iii) a diffuse interstitial pattern; (iv) scattered singly disposed giant cells; and (v) granulomatous vasculitis. Additional features included lymphocytic eccrine hidradenitis in those patients with drug reactions, hepatobiliary disease, and antecedent viral illnesses, tissue eosinophilia and erythrocyte extravasation in drug hypersensitivity, granulomatous vasculitis in patients with microbial triggers, drug hypersensitivity or RA, and lymphoid atypia in lesions of CTCL or drug hypersensitivity. Conclusions The cutaneous lichenoid and granulomatous reaction may reflect hepatobiliary disease, endocrinopathy, RA, Crohn’s disease, infection, or a drug reaction. One‐fifth of cases represent idiopathic lichenoid disorders. Lymphoproliferative disease or pseudolymphomatous drug reactions must be considered in those cases showing lymphoid atypia.