(12.14) A case of germinoma presenting as neurosarcoidosis: a clinical conundrum.

Germ cell tumors and neurosarcoidosis (NS) both rarely involve the hypothalamus and pituitary and are difficult to diagnose. Germinomas presenting as NS are extremely rare, only 9 cases have been described in the literature.

Case(s) Description :

A 20 year old African American woman was referred to endocrinology for hypercalcemia. She reported 3 months of fatigue and weight loss. She was polyuric and water deprivation test confirmed vasopressin deficiency (AVP-D). MRI showed 1.2 x 2.1 x 1.2 cm pituitary and infundibular enhancing lesion with scattered intraventricular subependymal enhancement, suggestive of NS. She was started on desmopressin (DDAVP) 0.05mg BID and referred to Rheumatology and Neurology. Laboratory workup including ACE level, AFP, ANCA and ds- DNA levels were normal. Chest X-ray and CT chest showed no evidence of hilar adenopathy. Lumbar puncture showed normal ACE level, no bacterial growth, slightly elevated protein and oligoclonal bands but no pleocytosis. Given MRI findings, CSF with inflammatory changes and negative CSF studies, neurology diagnosed her with NS and treated with Prednisone 30mg daily, Methotrexate 10mg/wk, and infliximab 5mg/kg Q6wk. Her clinical course was complicated by several admissions for altered mentation and hypernatremia. MRI 7 months after presentation showed mild decrease in size of the pituitary and infundibular mass (0.9 x 2.0 x 1.1 cm) but increase in intraventricular component. Prednisone was increased to 60mg/day and infliximab to 8mg/kg Q4wk. MRI 13 months after initial presentation showed marked intraventricular enlargement of the mass to 4.1 x 2.2 x 4.1 cm. Given progression despite treatment, a biopsy was performed, revealing a germinoma and no other germ cell tumor elements. She received proton therapy with near resolution of the mass and improvement in mentation however developed panhypopituitarism.

Discussion :

Germinomas are diagnostically challenging and can present similarly to NS on imaging, but treatment is different: first line treatment for germinomas is radiation whereas NS is treated with steroids and immunomodulators. Diagnostic delays have a significant impact on morbidity. We present a rare case of a germinoma that clinically mimicked NS. There have been only 9 other cases identified in the literature; outcomes were described in five: 3 patients died, 1 had ventricular hemorrhage post biopsy, 1 hydrocephalus. In our case, diagnosis was delayed by 13 months, and she responded well to radiation. Multidisciplinary treatment to differentiate and diagnose germinomas in a timely fashion is essential. Germinomas should be considered strongly in the differential of NS if the lesion does not respond to therapy as expected.