Endocrine Abstracts

Introduction: Leydig cell tumors (LCT) are rare testicular tumors, characterized by mostly benign etiology. Due to their secretory activity androgen- and/or estrogen-excess can occur.

Case report: A 42-year old patient with recent history of cerebrovascular incident was admitted to the hematology department for diagnostic work-up of new-onset erythrocytosis (hemoglobin 185 g/l [reference 127–163], hematocrit 0.53 [0.37–0.46]). Myeloproliferative neoplasia and other common causes of secondary erythrocytosis (i.e. obstructive sleep apnea, smoking) could be excluded. Remarkably, gonadotropin levels were suppressed on repetitive measurements (LH <0.1 U/l [1.7–8.6], FSH <0.1 U/L [1.5–12.4]). Total testosterone-/SHBG levels were in the mid-normal range (17.9 nmol/l [8.64–29] and 38.6 nmol/L [18.3–54.1], respectively) and estradiol was high-normal (154 pmol/l [41.4–159]). DHEA-S, androstendione, 17-OH-progesterone, AFP, beta-HCG and LDH were normal. The patient denied use of anabolic steroids and biochemical features of steroid abuse (i.e. low SHBG- and HDL-levels) were absent. Clinical examination was normal without gynecomastia, normal pattern of secondary hair and normal-sized, bilaterally descended testes without a palpable mass. Three months after initial presentation estradiol levels rose slightly above the upper limit of normal (198 pmol/l) whereas LH/FSH remained suppressed. Testicular ultrasound found a nodular structure of 1.5 cm in diameter. Tumor enucleation was performed, histologically proving Leydig cell tumor (LCT) without signs of malignancy. Postoperatively, hormone metabolism and hematocrit normalized completely during the following months.

Comment and conclusion: Up to 30% of LCT are associated with endocrine hypersecretion leading to a variety of clinical (i.e. gynecomastia, erectile dysfunction and loss of libido) and laboratory (i.e. erythrocytosis) findings which can gradually evolve–as seen in our patient. LCT exhibit specific patterns of endocrine alterations: enhanced aromatase activity leading to higher intratesticular and peripheral estradiol concentrations and secretion of inhibin causing a decline in FSH. However, most of the patients presenting preoperatively with testicular LCT have low-normal but unsuppressed LH-/FSH-levels. In our case the initial finding of suppressed gonadotropins, normal testosterone/estradiol and severe erythrocytosis is striking and the presence of unmeasured paraneoplastic secretion of other sex-steroids with LH-/FSH-suppressing and hematopoiesis-stimulating properties has to be postulated.