Infracentimetric parathyroid cysts in hyperparathyroidemia

Parathyroid cysts are rare, more frequently functional. Here we report 2 cases of infracentimetric parathyroid cysts identified in parathyroid adenomas resected for hyperparathyroidemia and hypercalcemia. Chronic parathyroiditis was associated. Chromogranin and E-cadherin/uvomorulin were expressed heterogeneously in the cyst lining and in parathyroid cells. In one of the cases, CD10 and CD56 were expressed by the luminal membrane of parathyroid cells. CD31 was expressed in interparathyroid cell monocyte/macrophage membrane as well as CD68, several cells showing also CD10 and/or CD56 expression. Ki67 was expressed in sparse parathyroid cells, some of binucleated cells or with nuclear clumps. In conclusion, heterogeneous E-cadherin expression in parathyroid cells may only indirectly related to cyst formation while CD56 and CD10 seem not to relate at all. The relevance of nuclear clumps and Azzopardi phenomenon as well as of the presence of disperse monocyte/macrophage-type cells for the parathyroiditis lesions remains to be further investigated.