A 46-year-old woman comes to the office with a painful rash involving her groin and legs that has been worsening over the last 2 weeks. She was diagnosed with diabetes mellitus 6 months ago but has no other medical problems other than occasional loose stools. Physical examination shows coalescing erythematous plaques with crusting and scaling at the borders and central areas of brownish induration. Biopsy of the lesions reveals superficial necrolysis. Which of the following laboratory abnormalities is most likely to be present in this patient?

Question

A 46-year-old woman comes to the office with a painful rash involving her groin and legs that has been worsening over the last 2 weeks.  She was diagnosed with diabetes mellitus 6 months ago but has no other medical problems other than occasional loose stools.  Physical examination shows coalescing erythematous plaques with crusting and scaling at the borders and central areas of brownish induration.  Biopsy of the lesions reveals superficial necrolysis.  Which of the following laboratory abnormalities is most likely to be present in this patient?

Quizplus · Accepted Answer

11ec160b_3917_9247_9249_85c115453b2b_MD0001_00 This patient most likely has a glucagonoma, a rare tumor arising from the alpha cells of the pancreatic islets of Langerhans. Glucagonomas secrete large quantities of glucagon, so affected patients often have hyperglycemia or overt diabetes mellitus. A characteristic skin finding is necrolytic migratory erythema, an elevated painful and pruritic rash typically affecting the face, groin, and extremities. Over time, small erythematous papules coalesce to form large, indurated plaques with a central clearing that often appears brown or bronze-colored. Diagnosis is made by detecting elevated levels of glucagon in the serum. (Choice A) Glucagon acts on the liver to promote amino acid oxidation and gluconeogenesis from amino acids. Circulating levels of amino acids are low in glucagonoma and thought to contribute to development of necrolytic migratory erythema. (Choice B) Elevated gastrin levels in patients with gastrinoma are associated with hypersecretion of gastric acid and resultant gastrointestinal ulceration. The peptic ulcers that occur with gastrinomas are often in unusual areas, such as the jejunum. Patients with gastrinomas can also have diarrhea and abdominal pain. (Choice D) Excess somatostatin secretion from a somatostatinoma typically presents with abdominal pain, gallbladder stones, constipation, hyperglycemia, and steatorrhea. These manifestations result from somatostatin-induced inhibition of insulin, glucagon, gastrin, secretin, and cholecystokinin secretion, and inhibition of gastrointestinal motility. (Choice E) High levels of vasoactive intestinal polypeptide (VIP) are seen in patients with a VIPoma, which typically presents with intractable diarrhea, hypokalemia, and achlorhydria. Patients are usually hypotensive due to dehydration and the vasodilatory effects of VIP. (Choice F) Diabetes mellitus is present in the majority of patients with glucagonoma, most likely due to excessive hepatic glucose production. Insulin levels tend to be normal but can be elevated secondary to hyperglycemia and glucagon-induced stimulation of the pancreatic beta cells. (Choice G) Zinc deficiency causes erythematous skin lesions (mainly around body orifices) that are predominantly vesicular and pustular. Other features include hypogonadism, impaired taste and smell, night blindness, and impaired wound healing. Although the skin lesions in zinc deficiency can resemble necrolytic migratory erythema, this patient's lack of additional findings and her recent diabetes mellitus diagnosis make glucagonoma more likely. Educational objective: Glucagonoma presents with hyperglycemia (often as newly diagnosed diabetes mellitus) and necrolytic migratory erythema (blistering erythematous plaques with central clearing) affecting the groin, face, and extremities. The diagnosis is made by detecting elevated glucagon levels. __________ References: The glucagonoma syndrome. Clinical and pathologic features in 21 patients. (http://www.ncbi.nlm.nih.gov/pubmed/8606627) Etiology and pathogenesis of necrolytic migratory erythema: review of the literature (http://www.ncbi.nlm.nih.gov/pubmed/15520626)

A 46-Year-Old Woman Comes to the Office with a Painful