CNC patients may present with a constellation of signs and symptoms including, but not limited to:
Skin pigmentation abnormalities
Pigmented skin lesions occur in more than 80% of patients. This includes lentigines, epithelial blue nevus, and café-au-lait spots. Lentigines increase in number after puberty and are characteristically distributed on the lips (crossing the upper vermilion border), conjunctiva, inner or outer canthi, and vaginal/penile mucosa.
Myxomas
Myxomas are recurrent and can be cutaneous (30-55%), cardiac (20-40%), and rarely osteochondromyxomas. Cutaneous myxomas usually occur in the eyelid, nipples, and genitalia. Cardiac myxomas may be found in any of the four chambers of the heart.
Endocrine tumors or overactivity
Effected endocrine glands include the adrenals, thyroid, pituitary, testicles and/or ovaries. Primary pigmented nodular adrenal disease (PPNAD), which causes ACTH-independent Cushing syndrome, is the most frequently reported endocrine tumor, affecting 75% of patients with CNC. Hypercortisolemia is often insidious in progression and cyclic. ACTH-dependent pituitary hypercortisolism, or adrenocortical cancer is limited to a small number of cases. Thyroid nodules occur early in life and are most commonly non-functioning thyroid follicular adenomas, rarely thyroid carcinoma. Growth hormone (GH)-producing pituitary adenomas arising from hyperplasia occur in 70% of CNC patients, however most present with asymptomatic GH, IGF-1, or prolactin elevations and rarely manifest with clinical acromegaly or gigantism. GH excess predisposes to myxoma growth, which increases risk for embolic cerebrovascular events, the most common cause of mortality in CNC. Large cell calcifying Sertoli cell tumors (LCCSCT) occur in more than three quarters of males with CNC. Ovarian cysts and tumors have also been reported, and rarely progress to ovarian carcinoma. CNC predisposes to dysglycemia from impaired insulin secretion.
Psammamomatous Melanotic Schwannomas (PMS)
PMS is a rare tumor of the nerve sheath that typically affects the gastrointestinal tract, and paraspinal sympathetic chain. Up to 10% of CNC patients exhibit PMS. A diagnosis is established when the affected individual exhibits two or more of the major diagnostic criteria listed above. Screening for pathogenic PRKAR1A variants can confirm the diagnosis in the setting of inconclusive clinical findings.