Carcinoma of unknown primary presenting as an apoplectic pituitary adenoma with suprasellar extension: a case report

Abstract Background Pituitary metastasis is a rare entity, accounting for less than 1% of all intracranial neoplasms. Common primary sites include the breast and lungs. Due to the indolent clinical nature of the disease and non-specific radiological findings, they are not easily discernible from more common pituitary lesions. Diagnosis is further complicated in the absence of an established underlying malignancy. Case presentation A 67-year old male patient presented with severe acute onset headache and vomiting, with associated left third cranial nerve palsy and a rapid decline in visual acuity. Imaging revealed a large 35.8 × 13.6 mm (CC x AP) haemorrhagic sellar lesion with suprasellar extension and compression of the optic chiasma. A primary non-functioning pituitary macro-adenoma was suspected and endoscopic trans-nasal trans-sphenoidal surgery under neuroimaging was undertaken. Histopathology of the necrotic tissue confirmed an apoplectic gonadotropinoma, with areas of malignant epithelial cells and a high mitotic rate (Ki-67 index of up to 30%). Primary disease, squamous cell carcinoma and neoplasms of bronchial and germ cell origins were excluded via immunohistochemistry. Whole body PET CT revealed no underlying malignancy. In view of the unknown origin of the primary tumour, the patient received radiotherapy to the pituitary fossa, and was kept on surveillance for five years. His visual function improved, and he remained stable post treatment. His diagnosis of primary lesion was still uncertain despite extensive histological and radiological investigations. Conclusion This case report underscores the challenges in diagnosis and treatment of metastatic pituitary lesions. Due to the unpredictable course of the disease, improvisation in management enabled favourable outcome.