Contributor: Gordon K. Klintworth
The term medullary carcinoma refers to a soft cellular carcinoma with little connective tissue. It can arise from a variety of cell types in different tissues, such as the thyroid gland and breast.
The medullary carcinoma of the thyroid gland arises from the parafollicular cells and secretes calcitonin. This tumor of neural crest origin accounts for <5% of thyroid cancers, but it develops in virtually all cases of multiple endocrine neoplasia syndrome type II. Medullary carcinoma of the thyroid gland can exhibit areas of squamous and mucinous change. Most sporadic cases of thyroid medullary carcinoma have somatic mutations in the RET gene. Histaminase is useful in identifying metastases of thyroid medullary carcinoma. Medullary carcinoma of the thyroid gland can exhibit areas of squamous and mucinous change).
Medullary carcinoma of the breast is an invasive tumor that lacks calcification. Microscopically it has highly pleomorphic cells and numerous mitotic figures. The periphery of the tumor is infiltrated by lymphocytes. Despite the ominous histopathologic features the prognosis is better than for the more common infiltrating ductal carcinoma and lobular carcinoma of the breast [carcinoma - breast].