Pituitary Metastasis of Clear Cell Renal Carcinoma Mimicking Pituitary Macroadenoma – Case Report

Introduction Pituitary tumors account for 25% of all primary brain tumors and for 15% of overall intracranial expansive masses. Pituitary metastases, in contrast, are a rare condition, estimated as 1.8% of all resected sellar lesions. We present here a rare case of clear cell renal carcinoma metastasis to the pituitary gland. Case Report A 65-year-old patient with holocranial headache and diplopia, whose physical examination showed right eye abduction palsy and ipsilateral anisocoria. Magnetic resonance imaging (MRI) of the pituitary revealed a heterogeneous mass in T1 weighted imaging with mild peripheral contrast enhancement and considerable growth during follow-up. Prolactin levels were high and dropped to normal after use of cabergoline, but remained normal even after the medication was halted. Biopsy was compatible with clear cell renal carcinoma. After surgery, the patient underwent radiotherapy, which was effective in reducing the volume of the lesion. Discussion Only 25 cases of pituitary metastasis arising from the kidney were reported in the literature between the years of 1957 and 2018. Metastases can reach the pituitary through hematogenous spread, cerebrospinal fluid, and contiguous bony lesions. Clinical presentation varies from vague complaints such as fatigue or headache to more specific signs like polyuria and polydipsia, and ∼ 60% of cases have clinical manifestations. Conclusion Case reports of pituitary metastases are low worldwide, with only 25 case reports of kidney metastases in over a 60-year period. The rarity of the lesions and hormonal alterations due to pituitary stalk compression can mislead diagnosis, and some patients may even never be diagnosed regarding their lower life span. In this report, radiotherapy was effective postresection, and accounts for a treatment option. All these issues account for the relevance of these case reports.