A case of Carney complex misdiagnosed as neurofibromatosis type 1 – Diagnostic difficulty in a rare disease

We experienced a diagnostically challenging case of Carney complex (CNC). A 24-year-old woman had a past history of surgical removal of multiple cutaneous tumors in the childhood. She was followed as a patient of neurofibromatosis type 1 (NF1) and referred to our hospital for further treatment after she grew up to adulthood. At our hospital, several cutaneous tumors were excised, and the pathological diagnosis was myxoma arising from not deep soft tissue but cutis (so-called cutaneous myxoma). Despite previous clinical diagnosis of NF1, because of the probability of CNC, detailed systemic examination was undertaken including radiological and endocrinological tests. Imaging techniques showed multiple lumps in both breasts, a mass in left atrium and nodular lesions in adrenal glands. Serum ACTH level was markedly suppressed. Surgically resected specimens revealed breast myxomas, cardiac myxoma and primary pigmented nodular adrenocortical disease (PPNAD). These findings met the diagnostic criteria for CNC. Genetic analysis revealed known non-sense mutation of PRKAR1A c.124C > T (p.R42X) (ClinVar ID 41382). Her 50-year-old mother was also shown to have cardiac myxomas, radiological finding of breast myxomatosis and the same PRKAR1A mutation as her daughter. In the present case, the accurate diagnosis of CNC was difficult not only because CNC is a rare disease but also because skin pigmentation was not obvious. Since cardiac myxoma might result in poor or fatal outcome, early and accurate diagnosis of CNC and subsequent systemic investigation including heart are important. Although pediatric cutaneous myxomas are rare, multiple cutaneous myxomas might suggest the possibility of CNC. In such cases, systemic investigation should be done for the accurate diagnosis.