Which MEN subset is associated with pheochromocytoma, medullary thyroid carcinoma, and hyperparathyroidism (Sipple’s syndrome)?

Which MEN subset is associated with pheochromocytoma, medullary thyroid carcinoma, and hyperparathyroidism (Sipple’s syndrome)?

• A. MEN I
• B. MEN IIa
• C. MEN IIb
• D. MEN III

Answer: (B)

This pattern shows a hereditary MEN syndrome where certain endocrine tumors co-occur. The combination of medullary thyroid carcinoma with pheochromocytoma and hyperparathyroidism is the hallmark of MEN type IIa (Sipple’s syndrome). In this form, the thyroid cancer and the adrenal tumor often appear together, and the parathyroid hyperplasia adds the hyperparathyroidism component, making this triad classic for IIa. In contrast, MEN IIb also includes medullary thyroid carcinoma and pheochromocytoma, but hyperparathyroidism is not typical; instead, patients have mucosal neuromas and a marfanoid body habitus. MEN I features parathyroid hyperplasia along with pancreatic islet cell tumors and pituitary adenomas, but not pheochromocytoma. Clinically, recognizing this triad is important because pheochromocytoma must be identified and treated before thyroid surgery to avoid hypertensive crises during the operation. Therefore, the described set of tumors best fits MEN type IIa (Sipple’s syndrome).

This pattern shows a hereditary MEN syndrome where certain endocrine tumors co-occur. The combination of medullary thyroid carcinoma with pheochromocytoma and hyperparathyroidism is the hallmark of MEN type IIa (Sipple’s syndrome). In this form, the thyroid cancer and the adrenal tumor often appear together, and the parathyroid hyperplasia adds the hyperparathyroidism component, making this triad classic for IIa.

In contrast, MEN IIb also includes medullary thyroid carcinoma and pheochromocytoma, but hyperparathyroidism is not typical; instead, patients have mucosal neuromas and a marfanoid body habitus. MEN I features parathyroid hyperplasia along with pancreatic islet cell tumors and pituitary adenomas, but not pheochromocytoma.

Clinically, recognizing this triad is important because pheochromocytoma must be identified and treated before thyroid surgery to avoid hypertensive crises during the operation. Therefore, the described set of tumors best fits MEN type IIa (Sipple’s syndrome).