Secondary Polycythemia Attributed To An Incidentally Discovered Luteinizing Hormone–Secreting Pituitary Adenoma: A Case Report

ABSTRACT Objective: Polycythemia is a rare and often unrecognized manifestation of a functional gonadotroph adenoma. Although silent gonadotroph macroadenomas are relatively common, functional gonadotroph adenomas are rare. Methods: We report a case of a 66-year-old patient treated for chronic idiopathic polycythemia for at least 10 years, in whom a large pituitary lesion in a cerebral computed tomography (CT) scan was incidentally discovered in a cerebral computed tomography (CT) scan. Results: The patient presented with nasal erythromelalgia and facial erythrosis while being treated with hydroxyurea for primary polycythemia. CT findings and biochemical analyses revealed a large pituitary tumor and increased testosterone and luteinizing hormone (LH) levels. Following resection of the tumor, immunostaining confirmed positive staining for follicle-stimulating hormone and LH, leading to the diagnosis of a functional gonadotroph adenoma. Due to persistent radiologic and biochemical disease after surgical resection, tumoral and secretory control was achieved with combination treatment with long-acting octreotide and cabergolide. Polycythemia was resolved after the initiation of the treatment for the gonadotroph adenoma. Conclusion: This case of a rare LH-secreting pituitary adenoma illustrates that physicians should be aware of rare causes of polycythemia. Testosterone measurement should always be considered, especially in cases of polycythemia of unknown origin. In our case, the combination of treatment with somatostatin analogues and dopaminergic agonists was efficacious in reducing both the secretory and tumoral component that led to resolution of polycythemia. Abbreviations: FSH = follicle-stimulating hormone; Hb = hemoglobin; Hct = hematocrit; IHC = immunohistochemistry; LAR = long-acting release; LH = luteinizing hormone; MRI = magnetic resonance imaging