[Pigmented micronodular dysplasia of the adrenal glands and Carney complex]

Carney complex presenting with a unilateral adrenocortical nodule: a case report

INTRODUCTION

Carney complex is an autosomal dominant syndrome with multiple neoplasms in different sites, including myxomas, endocrine tumors and lentigines lesions. To the best of our knowledge, this is the first report of Carney complex presenting with a unilateral adrenal adenoma associated with a pituitary incidentaloma.

CASE PRESENTATION

A 27-year-old Iranian woman was referred to our endocrinology clinic with amenorrhea and hirsutism, further confirming a diagnosis of adrenocorticotropic hormone-independent Cushing's syndrome. The cause was believed to be a right adrenocortical adenoma based on a computed tomography scan. Our patient underwent a right laparoscopic adrenalectomy and pathological examination revealed pigmented micronodular adrenal hyperplasia. Pituitary magnetic resonance imaging also documented a microadenoma that was considered to be an incidentaloma based on normal pituitary function tests. Recurrence of hypercortisolism led to a left laparoscopic adrenalectomy, providing further evidence for the diagnosis of primary pigmented nodular adrenocortical disease. Carney complex was established in light of her history of cardiac myxomas.

CONCLUSION

We present what we believe to be the first case of Carney complex presenting with a unilateral adrenocortical adenoma in association with a pituitary incidentaloma. Although primary pigmented nodular adrenocortical disease is rare as a component of Carney complex, it should be considered in the differential diagnosis of Cushing's syndrome. Rarely, adrenal and pituitary imaging can be misleading.

PRKAR1A mutations in primary pigmented nodular adrenocortical disease

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare primary bilateral adrenal defect causing corticotropin-independent Cushing's syndrome. It occurs mainly in children and young adults. Macroscopic appearance of the adrenals is characteristic with small pigmented micronodules observed in the cortex. PPNAD is most often diagnosed in patients with Carney complex (CNC), but it can also be observed in patients without other manifestations or familial history (isolated PPNAD). The CNC is an autosomal dominant multiple neoplasia syndrome characterized by the association of myxoma, spotty skin pigmentation and endocrine overactivity. One of the putative CNC genes has been identified as the gene of the regulatory R1A subunit of protein kinase A (PRKAR1A), located at 17q22-24. Germline heterozygous inactivating mutations of PRKAR1A have been reported in about 45% of patients with CNC, and up to 80% of CNC patients with Cushing's syndrome due to PPNAD. Interestingly, such inactivating germline PRKAR1A mutations have also been found in patients with isolated PPNAD. The hot spot PRKAR1A mutation termed c.709[-7-2]del6 predisposes mostly to isolated PPNAD, and is the first clear genotype/phenotype correlation described for this gene. Somatic inactivating mutations of PRKAR1A have been observed in macronodules of PPNAD and in sporadic cortisol secreting adrenal adenomas. Isolated PPNAD is a genetic heterogenous disease, and recently inactivating mutations of the gene of the phosphodiesterase 11A4 (PDE11A4) located at 2q31-2q35 have been identified in patients without PRKAR1A mutations. Interestingly, both PRKAR1A and PDE11A gene products control the cAMP signaling pathway, which can be altered at various levels in endocrine tumors.