Hematoxylin-eosin–stained sections of a mucosal nodule revealed unencapsulated masses of fascicular Schwann cells surrounded by a thickened perineurium. The tumor cells were positive for S100 protein antigen on immunohistochemical analysis. The serum calcitonin level was increased to 5640 pg/mL (reference value, <27 pg/mL). Urinary catecholamine metabolite concentrations were highly increased. A complete workup revealed a pheochromocytoma of the right adrenal gland (6 × 4 cm) as well as medullary thyroid carcinoma (MTC) with lymphogenic metastasis. Intestinal ganglioneuromatosis, with resulting megacolon, was also found. A thyroidectomy, a bilateral cervical lymphonodectomy, and a right adrenalectomy were performed, but the serum calcitonin level remained high after surgery, suggesting incomplete removal of the MTC or occult metastases. Polymerase chain reaction amplification and single-stranded conformational polymorphism of genomic DNA of peripheral blood mononuclear cells revealed a mutation of exon 16 in the RET proto-oncogene. Sequencing confirmed a germline point mutation in codon 918 (M918T) in this gene.
Soft Nodules at the Tip of the Tongue of a 26-Year-Old Man—Diagnosis. Arch Dermatol. 2003;139(12):1647-1652. doi:10.1001/archderm.139.12.1647-a