A 52-year-old woman presents with a 6-month history of progressive, migratory erythematous plaques with central erosion and crusting over the perineum, groin, and perioral region. She reports new-onset diabetes mellitus and weight loss. Laboratory investigations reveal serum glucagon 850 pg/mL (normal <150 pg/mL) and CT abdomen shows a 6 cm mass in the pancreatic tail with hepatic metastases. The cutaneous manifestation marked **B** in the diagram is pathognomonic for which underlying neoplasm?
A. Pancreatic beta-cell neuroendocrine tumor (insulinoma)
B. Gastrinoma (gastric acid-secreting neuroendocrine tumor)
C. Pancreatic alpha-cell neuroendocrine tumor (glucagonoma)
D. Somatostatinoma (somatostatin-secreting neuroendocrine tumor)
Explanation
Why Pancreatic alpha-cell neuroendocrine tumor (glucagonoma) is right
Necrolytic migratory erythema (NME), marked as B in the diagram, is the pathognomonic cutaneous hallmark of glucagonoma syndrome. The clinical presentation—migratory annular plaques with central erosion and crusting in an intertriginous and periorificial distribution (perineum, groin, perioral), combined with new-onset diabetes, weight loss, and markedly elevated serum glucagon (>500 pg/mL)—is diagnostic of glucagonoma. NME results from glucagon-driven catabolism of amino acids, leading to deficiency of zinc, essential fatty acids, and niacin, which causes epidermal necrolysis. The pancreatic tail mass with hepatic metastases confirms the diagnosis. (Bolognia Dermatology 5e; Harrison's Endocrinology 4e)
Why each distractor is wrong
Pancreatic beta-cell neuroendocrine tumor (insulinoma): Causes hypoglycemia and Whipple's triad (confusion, sweating, palpitations), not hyperglycemia or NME. No characteristic dermatosis.
Gastrinoma (gastric acid-secreting neuroendocrine tumor): Presents with severe peptic ulcer disease and chronic diarrhea (Zollinger-Ellison syndrome), not NME or the characteristic migratory periorificial dermatitis. Serum gastrin is elevated, not glucagon.
Somatostatinoma (somatostatin-secreting neuroendocrine tumor): Causes achlorhydria, steatorrhea, and weight loss but does NOT produce NME. The dermatologic hallmark is absent, and serum somatostatin (not glucagon) is elevated.
High-YieldNEET PG
NME is the ONLY cutaneous paraneoplastic dermatosis pathognomonic for glucagonoma; always check serum glucagon in any patient with migratory periorificial erosive dermatitis and new-onset diabetes.
Bolognia Dermatology 5e; Harrison's Endocrinology 4e
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