OBJECTIVE To report the diagnostic difficulties encountered in a case of glucagonoma. METHODS We provide a literature review and present the clinical findings, pertinent laboratory data, and results of related studies in a patient with a glucagonoma. RESULTS A 54-year-old-man, with no relevant history of endocrine disorders, presented to the hospital with a 5-year history of recurrent stomatitis and glossitis, a more recent weight loss of 11.5 kg, and recurrent pruritic maculae on the scalp in conjunction with raised erythematous maculae in the scrotal region and perineum that gradually migrated to the distal extremities, becoming bullous and painful. The patient was hospitalized, and because of the dermatologic findings suggestive of necrolytic migratory erythema, the presence of a glucagonoma was suspected. His blood glucose levels were in the normal range. Glucagon levels were found to be elevated, and imaging studies confirmed the presence of an enlarged mass in the pancreatic tail, without evidence of extension to surrounding structures. Liver metastatic lesions were also excluded. After surgical removal of the tumor, the skin and oral mucosal lesions disappeared spontaneously. The histologic appearance and immunohistochemical staining results confirmed the diagnosis of a glucagonoma. Subsequently, all related symptoms resolved, and the glucagon levels normalized. CONCLUSIONS The diagnosis of glucagonoma is often delayed. Clinicians should be aware of the unusual initial manifestations of this tumor and the potential for less than a full spectrum of the characteristic features of the glucagonoma syndrome.