Reversible generalized cutaneous hyperpigmentation: presenting manifestation of pernicious anemia.

TL;DR: It is concluded that the generalized cutaneous hyperpigmentation was secondary to vitamin B12 deficiency, and treatment with intramuscular cyanocobalamin responded dramatically to treatment.

Abstract: A 16-year-old boy presented with progressive and asymptomatic mottled hyperpigmentation that had been there for four years. The lesions had appeared initially on his arms and extended gradually over the years to involve the trunk, face, and extremities (Fig. 1). The palms and soles were prominently involved, and fingernails showed longitudinal hyperpigmented streaks (Fig. 2). The mucous membranes, teeth, and hair appeared normal. Systemic examination was unremarkable, and routine blood investigations were normal on first presentation. Histopathological examination of a skin biopsy revealed a lymphocytic inflammatory infiltrate in the upper dermis with numerous melanophages. Four months later, the patient began to complain of nausea, decreased appetite, significant weight loss, and worsening of cutaneous hyperpigmentation. Laboratory studies were performed, revealing pancytopenia (hemoglobin 8.0 g/dl, mean corpuscular volume 79, whole blood count 1270/mm, platelets 55,000/mm). The blood smear demonstrated marked anisocytosis and poikilocytosis, and the bone marrow aspirate showed megaloblastic changes. Vitamin B12 serum level was low (72.5 pg/ml), and folate level was normal. Anti-intrinsic factor antibody and antiparietal cell antibody were positive. Diagnosis of pernicious anemia was established and treatment with intramuscular cyanocobalamin started. The anemia responded dramatically to treatment, and the degree of hyperpigmentation decreased noticeably after nine months (Fig. 3). We conclude that the generalized cutaneous hyperpigmentation was secondary to vitamin B12 deficiency.