Abstract: MON 484
Pituitary Carcinoma Presenting with Extensive Orbital Inflammation from Development of a Delayed Bone Metastasis
Presenter: Tasneem Kaleem
Introduction: Pituitary carcinoma is a rare condition defined solely by pathological evidence of a pituitary tumor at a distant location or noncontiguous site from the original adenoma. Pituitary carcinoma comprises up to 0.2% of all pituitary tumors and portends a poor prognosis. Here we present a case of a corticotroph pituitary adenoma presenting with extensive orbital inflammation from development of a bone metastasis.view more
Introduction: Pituitary carcinoma is a rare condition defined solely by pathological evidence of a pituitary tumor at a distant location or noncontiguous site from the original adenoma. Pituitary carcinoma comprises up to 0.2% of all pituitary tumors and portends a poor prognosis. Here we present a case of a corticotroph pituitary adenoma presenting with extensive orbital inflammation from development of a bone metastasis.
Clinical Case: A 75 year old female with history of hypothyroidism and Type II diabetes presented with diplopia and weight gain for several weeks. Physical exam demonstrated right sixth nerve palsy and moon facies. Pertinent hormonal studies include ACTH 116 pmol/L (4.5-20 pmol/L), Prolactin 23.9 ng/mL (<14 ng/mL), and 24 hour urine free cortisol 172 (3.5-45 mcg). Low dose dexamethasone test cortisol level was 15.4 mg/dL (<1.8 mg/dL). Magnetic Resonance Imaging (MRI) revealed a pituitary lesion measuring 19x16x18 mm displacing pituitary stalk and involving the right cavernous sinus. Findings were consistent with corticotroph adenoma with stalk effect. She underwent transphenoidal pituitary resection. Pathology showed an atypical corticotroph adenoma with Ki67 index of 8%. Tumor cells were positive for ACTH. Postoperatively, MRI displayed residual tumor in the right cavernous sinus, an ACTH level of 71.7 pmol/L and 24 hour urine free cortisol of 119 mcg. She was initiated on Pasireotide and underwent adjuvant radiation therapy (RT), 5040 cGy in 28 fractions. Post RT her sixth nerve palsy, urine cortisol and ACTH normalized. Serial MRIs were stable and she remained in biochemical remission until 23 months post RT, when she presented with swelling and pain of the right eye and return of cushingnoid features. MRI showed periorbital inflammation and a focal lesion in right sphenoid bone. Follow up 24 hour urine cortisol was 616 mcg and ACTH was 127 pmol/L. She was treated for orbital cellulitis and started on Pasireotide. She underwent biopsy and culture of right sphenoid bone lesion. Cultures were all negative. Pathology was consistent with known corticotroph pituitary adenoma, confirming bone metastasis and diagnosis of pituitary carcinoma.
Conclusion: Pituitary carcinomas most commonly present with metastatic spinal or meningeal lesions. Rarely, it can present in the bone with associated inflammation. This case demonstrates the severity of inflammatory changes that can occur and subsequently be misdiagnosed as infection or mask a metastatic lesion. Thus, despite aggressive treatment of original tumor, delayed bone metastasis can occur.