Lichen planus pemphigoides presenting with a strikingly unilateral distribution

A 44‐year‐old Pakistani woman presented with a unilateral eruption of 2 months’ duration. She was in her usual state of health when she awoke one morning with an acute blistering eruption in the right axilla. At that time she also began to experience “rough spots” on the buccal mucosa. Approximately 4 days later, lesions, including small blisters, appeared at multiple other sites, all in a right‐sided distribution. The patient had an 8‐year history of hypothyroidism and was treated with levothyroxine. Physical examination revealed a widely distributed and strikingly right‐sided eruption. Dark brown macules and patches measuring 0.1–1.2 cm, some of which were confluent, were located in the right axillary area at the site of previous blister formation ( Fig. 1a ). Close inspection revealed that some of these lesions had a glistening and violaceous appearance at their periphery. Discrete, small, flat‐topped papules with similar qualities were also present at this location. Lichenoid lesions were evident in multiple other (a) Hyperpigmented macules and patches in the right axillary region. Some of these lesions had a glistening, violaceous, and raised quality at the periphery (white arrow) suggesting post‐inflammatory hyperpigmentation secondary to lichen planus. (b) Lichenoid lesions in the intergluteal area and the right buttock image image right‐sided areas, including the submammary area, lower back, intergluteal region, buttock ( Fig. 1b ), inguinal crease, and knee. Similar lesions on the right arm appeared Koebnerized, extending linearly along the lateral aspect of the mid upper arm to the mid forearm. Examination of the oral mucosa revealed violaceous patches with a lacy pattern on the buccal mucosa. The remainder of the examination was unremarkable. Routine bloodwork was noncontributory. Hepatitis C antibodies were negative. Thyroid function tests were within the range of normal, as were a chest X‐ray examination and routine urinalysis. Punch biopsy of a lower back lichenoid lesion demonstrated a subepidermal bulla with festooning of the dermal papillae ( Fig. 2a ). Other features included orthokeratosis, a sparse superficial dermal infiltrate (composed of lymphocytes, histiocytes, and eosinophils), and numerous melanophages. A second biopsy from this region was divided for routine histopathology and direct immunofluorescence (DIF). Histopathologic examination was consistent with lichen planus. The features included compact orthokeratosis, hypergranulosis, and irregular, saw‐toothed acanthosis. The basal layer exhibited marked vacuolar change and a band‐like lymphohistiocytic infiltrate was present in the superficial‐most dermis ( Fig. 2b ). DIF revealed a conspicuous and linear deposition of immunoglobulin G (IgG), C3, and fibrinogen along the epidermal basement membrane zone. There was no staining with antisera to IgM or IgA. Colloid bodies were not identified. Indirect immunofluorescence studies were negative. (a) Biopsy specimen of lichenoid papule on the lower back demonstrated features of bullous pemphigoid. These included subepidermal blister formation and festooning of the dermal papillae (hematoxylin and eosin; original magnification, ×50). A sparse dermal chronic inflammatory infiltrate was also present. (b) Second biopsy specimen of a lichenoid lesion from the lower back demonstrated features of lichen planus, including basal layer vacuolarization and a band‐like lymphohistiocytic infiltrate (hematoxylin and eosin; original magnification, ×100) image Correlating the clinical, histopathologic and immunopathologic findings, a diagnosis of lichen planus pemphigoides was made. Treatment was initiated with prednisone, 60 mg daily, and tapered over the next 4 weeks as the eruption gradually resolved. Topical clobetasone ointment was prescribed for an additional 2 weeks. There have been no recurrences or new blister formation since that time.