Broad bands of fibrosis and entrapped parathyroid cells may raise concern for a parathyroid carcinoma, but prior surgery was performed on this patient.
The fibrotic bands compartmentalize the parathyroid tissue.
Hemosiderin and hemorrhage can be a clue to prior surgical manipulation.
One of the criteria for separating benign parathyroid neoplasms (hyperplasia and adenoma) from parathyroid carcinoma is the presence of invasion into surrounding structures. However, there are several instances where one must proceed with caution.
For example, there may be entrapment of tumor cells in the capsule in an adenoma, and this is not capsular invasion. Furthermore, post-surgical manipulation (i.e. removing a parathyroid adenoma) can lead to scarring and hemorrhage in residual parathyroid tissue. The scarring may mimic the broad fibrous septae (often seen in parathyroid carcinoma) or perhaps capsular invasion (Fletcher).