Necrobiosis lipoidica associated with sarcoidosis

We report the case of a 40-year-old African-American female with biopsy-proven pulmonary sarcoidosis who developed atrophic plaques on her shins, trunk, and scalp that were clinically and histologically consistent with necrobiosis lipoidica (NL). The lesions appeared 3 years after her diagnosis of sarcoidosis, and progressed despite chronic prednisone. Sarcoidosis and NL are granulomatous skin disorders reported to coexist in the same patient only 10 times in the literature. Including the current case, patients have been exclusively females around middle age, and have greater tendencies to develop typical cutaneous sarcoidosis. The incidence of diabetes is rare in this group. Like typical NL, NL associated with sarcoidosis tends to ulcerate, and is difficult to treat. Interestingly, there are six similar cases reported in the literature of patients with sarcoidosis who developed lesions clinically and behaviorally consistent with NL, but received a final histological diagnosis of sarcoidosis. These cases share very similar demographics and clinical features with cases of true NL associated with sarcoidosis, and often have more ambiguous histology containing features of both cutaneous sarcoidosis and NL. Comparing the two sets of cases raises the possibility of a final common disease pathway shared by these two granulomatous skin disorders.