SAT-128 An Uncommon Case of Squamous Cell Carcinoma of the Vulva with Metastasis to the Thyroid Gland

Background: Distant metastasis from Squamous Cell Carcinoma (SCC) of the Vulva is very rare and typically associated with poor outcomes. In the literature, there have been no reported cases of vulvar SCC with metastasis to the thyroid, which augments the uniqueness of the case we are presenting. Clinical Case: A 29-year-old female was hospitalized for abdominal pain & altered mental status. Labs showed calcium 21 (RR 8.5-10.5 mg/dL) with iPTH 4.3 (RR 12-88 pg/mL). Imaging revealed an 8.6 x 7.2 cm right thyroid mass (solid with cystic internal components, hyperechoic to isoechoic, wider than tall, lobulated margins, punctate echogenic foci occupying nearly the entire right lobe, minimal vascularity), mildly effacing the trachea. There were also extensive lesions consistent with systemic metastasis involving the left hilar lymph nodes, pre-tracheal lymph nodes, right hepatic lobe, head of pancreas, retroperitoneal lymph nodes, right inferior pubic ramus, proximal right humerus, left humerus, proximal femur & frontal lobe of the brain. Hypercalcemia of malignancy from an unknown cancer was diagnosed. FNA biopsy of the thyroid mass was consistent with atypia of undetermined significance. Liver biopsy showed evidence of high grade carcinoma with non-calcitonin producing neuroendocrine differentiation. Labs showed serum serotonin 11 (RR 56-244 ng/mL), CA 19-9 < 0.8 (RR 0-35 U/mL), alpha-fetoprotein 2.12 (RR 0-9 ng/mL), CEA 20.97 (RR 0-2.9 ng/mL), PTHrP 33 (RR 14-27 pg/mL), 1,25OH Vit D 18 (RR 18-72 pg/mL), chromogranin A 189 (RR 25-140 pg/mL), & calcitonin < 2 (RR < 5 pg/mL). A vaginal lesion was discovered on exam & biopsy showed squamous cells with cytopathic effect of Herpes Simplex Virus (confirmed with immunohistochemical stain). Subsequent biopsy of the brain & core needle biopsy of the thyroid showed morphology similar to a concurrent biopsy of a vulvar lesion also found on exam: poorly differentiated SCC. The patient was diagnosed with vulvar SCC with extensive metastasis. Her hospital course was complicated by atrial fibrillation, acute respiratory failure, & sepsis. She, unfortunately, passed away from her severe morbidities. Discussion: Metastasis to the thyroid is an infrequent occurrence. It is commonly encountered in breast, lung & renal cell carcinomas. It can occur due to direct spread from adjacent tissues or by lymphatic or hematogenous spread. Thyroid gland metastasis is more commonly seen in patients with aggressive or widespread carcinomas, especially by hematogenous route, due to the thyroid’s extensive vascularity. Conclusion: Thyroid gland metastasis, particularly due to vulvar SCC, is a rare entity with a poor prognosis. In patients with extensive poorly differentiated carcinoma such as our patient, it is of utmost importance to identify suspicious thyroid nodules and perform comprehensive diagnostic testing to facilitate timely intervention for improved outcomes.