SUN-493 Spontaneous Remission of Primary Hyperparathyroidism Presenting as Acute Chest and Neck Pain

Primary hyperparathyroidism is characterized by sustained hypercalcemia and is most often caused by a parathyroid adenoma. The disease is often indolent, without measurable morbidity and consequently followed without specific treatment. If therapy is chosen the surgical removal of the adenoma is the therapy of choice. Herein we report a 58 years old female with spontaneous remission of primary hyperparathyroidism. The patient was first seen in 2009 with high PTH and slightly high calcium level. She had the US identification of a likely parathyroid adenoma, 1.4 x 0.6 x 0.5 cm lying inferior to the left thyroid lobe. Her serum calcium was at the upper limits of normal, bone density was with positive T scores at wrist, spine and hip, and there was no history of renal stones. Options were discussed and she choose surveillance rather than surgery. She returned in 2011 when a similar structure was seen on repeat US. She was lost to follow up until in 7/2017 when she experienced upper chest pressure “like something was stuck in my esophagus" which radiated to left breast, shoulder blade, and left neck. She went to ER where CT of the chest identified a 1.8 x 0.9 cm heterogenic mass inferior to the left thyroid lobe, judged atypical for parathyroid adenoma, with a differential including an inflammatory process or esophageal duplication cyst. Lab from ER indicated Ca 10.3 mg/dl. Cardiac evaluation was negative and her pain resolved over 4 days. ENT and GI evaluations were unrevealing and she was prescribed Pepcid. When she returned to our office 8/2017, her biochemical studies showed normal serum levels of calcium (9.5 mg/dl) and PTH (41 pg/mL). Her subsequent neck ultrasound failed to identify the lesion inferior to the left thyroid lobe. Spontaneous remission of primary hyperparathyroidism is considered to be an extremely rare event and was first described in 1946. The most common cause for a spontaneous remission of primary hyperparathyroidism appears to be an infarction of the parathyroid adenoma (1). A larger sized adenoma (>2 cm) appears to be a risk factor for infarction according to a case series described by Kovacs et al. in 1998 (1). Therefore, hemorrhage and infarction might be a reasonable hypothesis to explain the pain and parathyroid enlargement and subsequent disappearance of the adenoma, which led to the spontaneous remission of primary hyperparathyroidism. References:(1): Kovacs KA, Gay JD. Remission of primary hyperparathyroidism due to spontaneous infarction of a parathyroid adenoma. Case report and review of the literature. Medicine (Baltimore). 1998; 77(6):398-402.