**Core Concept:**
MEN-2 (Multiple Endocrine Neoplasia type 2) is a genetic disorder characterized by the development of tumors in endocrine glands, particularly the parathyroid, thyroid, and adrenal glands. MEN-2 is caused by mutations in the RET proto-oncogene, leading to uncontrolled cell proliferation. This condition is classified into three types: MEN-2A, MEN-2B, and MEN-2C. Each type is associated with specific endocrine tumors and clinical features.

**Why the Correct Answer is Right:**
The correct answer, D, refers to an endocrine tumor that is NOT specifically associated with MEN-2. In MEN-2, multiple endocrine tumors are caused by RET proto-oncogene mutations. Among the options provided, A, B, and C are associated with MEN-2A, MEN-2B, and MEN-2C, respectively. Therefore, D is the correct answer because it represents a tumor type that is NOT directly linked to MEN-2.

**Why Each Wrong Option is Incorrect:**
A. MEN-2A is characterized by medullary thyroid carcinoma (MTC), primary hyperparathyroidism, and pheochromocytoma. This option is incorrect because it represents a combination of clinical features associated with MEN-2A.
B. MEN-2B is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and mucosal neuromas. This option is incorrect as it represents a combination of clinical features associated with MEN-2B.
C. MEN-2C is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and primary hyperparathyroidism. This option is incorrect because it represents a combination of clinical features associated with MEN-2C.

**Clinical Pearl:**
In the context of endocrinology, it is essential to understand the distinct clinical features associated with MEN-2A, MEN-2B, and MEN-2C to differentiate between various types of multiple endocrine neoplasia syndromes. This differentiation is crucial for appropriate diagnosis, management, and surveillance for patients presenting with these syndromes. Early diagnosis and treatment help prevent complications and improve patient outcomes.