Objective: The presence of primary hyperparathyroidism (PHPT) and Klinefelter syndrome (KS) is rare, and its association with KS mosaicism is even rarer. We report an unusual combination of these entities with a mild phenotype of KS.
Methods: The patient was a 44-year-old male with a history of PHPT who had recurrent urolithiasis despite being treated with a successful parathyroidectomy. On examination, he had axillary hair growth, bilateral gynecomastia, a large port-wine stain at the right hemithorax and upper right limb, and genitalia and pubic hair corresponding to Tanner IV classification with small, normal consistency testicles.
Results: Laboratory findings were unremarkable except for a slightly elevated luteinizing hormone, which was normal on repeat testing. Because of the picture of unexplained gynecomastia, laboratory findings, and low-volume testis, a diagnosis of KS was considered. Chromosomal analysis revealed a rare 45,X/46,XY/47,XXY/48,XXYY/48,XXXY KS mosaic.
Conclusions: KS phenotypes are largely variable, and their association with PHPT remains to be elucidated.
Keywords: KS, Klinefelter syndrome; Klinefelter syndrome; LH, luteinizing hormone; PHPT, primary hyperparathyroidism; PTH, parathyroid hormone; hyperparathyroidism; mosaicism; nephrolithiasis.
© 2021 AACE. Published by Elsevier Inc.