A Novel Variant in the Calcium-Sensing Receptor Associated with Familial Hypocalciuric Hypercalcemia and Low-to-Normal PTH

Figure 1

Bone imaging and bone and parathyroid histology. (a–f) Bone. (a) Initial MRI in 2013 showing bony lesion on the left iliac wing (bright area, white arrow) and (b–d) bone biopsy from 2013 reported as consistent with osteitis fibrosa cystica. Woven bone with marrow fibrosis (b), multinucleated osteoclasts with bone resorption (c), and osteoblastic rimming of new woven bone (d). (e) Repeat biopsy showing woven bone and peritrabecular fibrosis, with magnified portion (f). (g, h) Parathyroid. (g) Left lower parathyroid partial resection H&E stain, the specimen weighed 20 mg and measured 0.4 cm. Parenchyma was approximately 50% parathyroid epithelial cells (predominantly chief cells) and 50% adipocytes. (h) Right upper parathyroid gland biopsy, H&E stain, the specimen weighed 16 mg and measured 0.6 cm. Compared to that in (g), the parathyroid parenchyma is composed of approximately 80% parathyroid epithelial cells (predominantly chief cells) and 20% adipocytes. The amount of cellularity may be seen in normal parathyroid tissue or in hyperplasia. An additional biopsy of the left upper parathyroid gland was performed and was within normal limits based on weight and cellularity (not shown).

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