Histopathological evaluation of dopamine receptor D2 expression in symptomatic gonadotroph pituitary neuroendocrine tumors: a case series including a rare metastatic case responsive to a dopamine agonist

Functioning gonadotroph pituitary neuroendocrine tumors (Gn-PitNETs) cause ovarian hyperstimulation. We report Gn-PitNETs, including a distant metastasis case responsive to a dopamine agonist (DA), cabergoline. A 10-year-old girl presented with ovarian enlargement and elevated FSH levels (33.7 mIU/mL). A pituitary tumor was resected and confirmed as a Gn-PitNET. Radiotherapy for residual tumor improved ovarian enlargement. At age 20, ovarian enlargement recurred and cabergoline relieved symptoms and decreased FSH levels. At age 35, ovarian enlargement recurred after discontinuing cabergoline but improved with its reinstatement. Liver biopsy confirmed metastatic Gn-PitNET and DRD2 positivity. A 26-year-old woman presented with ovarian enlargement and elevated FSH levels (31.6 mIU/mL). A pituitary tumor was resected and confirmed as a Gn-PitNET with negative DRD2. FSH levels normalized, and ovarian size improved. A 48-year-old man presented with bitemporal hemianopia. FSH levels were elevated (251.4 mIU/mL) without testicular enlargement. The pituitary tumor was resected, improving hemianopia and normalizing FSH levels. Histopathology confirmed a Gn-PitNET with strong FSH staining and DRD2 positivity. In a rare case of metastatic Gn-PitNET, cabergoline was associated with tumor stability and hormone control. Further studies may clarify whether DRD2 expression can help predict DA responsiveness in refractory tumors. (200/200 words)