Multiple Myeloma Presenting as Massive Amyloid Deposition in a Parathyroid Gland Associated with Amyloid Goiter: A Medullary Thyroid Carcinoma Mimic on Intra-operative Frozen Section

Abstract

Clinical examples of amyloid deposition in parathyroid glands are exceedingly rare and usually present as an incidental finding in a patient with amyloid goiter. Here, we present the first histologically documented case of parathyroid amyloid deposition that presented as a mass. The patient did not have hyperparathyroidism. The parathyroid gland was submitted for intra-operative frozen section and concern for medullary thyroid carcinoma was raised. An important histologic clue arguing against medullary thyroid carcinoma was the evenly dispersed nature of the amyloid. Histologic perinuclear clearing and parathyroid hormone immunohistochemistry confirmed parathyroid origin on permanent sections. The patient was also found to have associated amyloid goiter. Mass spectrometry of the amyloid showed it to be composed of kappa light chains. On further work-up, the patient was diagnosed with multiple myeloma. Awareness of parathyroid amyloid deposition is important as it is a histologic mimic of medullary thyroid carcinoma, especially on frozen section. Amyloid typing with evaluation for multiple myeloma in any patient with kappa or lambda light chain restriction is also important.

A Herald of Plasma Cell Myeloma: A Report of Malignant Plasma Cells Identified in Parathyroid Adenoma and a Review of Non-parathyroid Malignancies in Parathyroid Glands

“…We believe ours to be the first reported case of a hematopoietic malignancy directly involving a parathyroid adenoma, as well as the first reported case in which an otherwise unknown hematopoietic malignancy was diagnosed via identification of tumor cells during microscopic evaluation of parathyroid tissue. A recently reported case of multiple myeloma diagnosed following histologic evaluation of a parathyroid gland involved by massive amyloid deposition without myeloma cells further illustrates the wide variation in disease processes which may manifest in the parathyroid glands [18].…”

“…Random "endocrine-type" nuclear atypia (enlargement and hyperchromasia) is often identified and is not of diagnostic or prognostic significance [17]. Cystic change has been described in adenomatous parathyroid nodules, as well as spindle cell changes and papillary architectural formation [18]. Metastatic tumors rarely involve the parathyroid glands, with autopsy studies demonstrating parathyroid metastases in up to approximately 12% of deceased patients with known malignancies [13].…”

Amyloid goiter - A rare case report and literature review

“…A typical histological picture will show extensive widespread infiltration [ 10 , 11 ] with evidence of follicular distortion and fatty metaplasia [ 10 ]. The exact mechanism responsible for fatty metaplasia is unknown.…”

“…Evidence of thyroid micro deposits is seen in more than 80% of medullary thyroid cancers [ 16 , 17 ] and in 30–80% of patients with amyloidosis [ 18 ]. Those are typically incidental findings not leading to Amyloid Goiter [ 11 ].…”

“…In secondary amyloidosis, amyloid goiter has been described to occur as a sequela of long standing Familial Mediterranean Fever [ 4 , 23 ], Inflammatory bowel disease [ 24 ], rheumatoid arthritis [ 24 ], TB [ 1 ] and bronchiectasis [ 25 ]. Overall amyloid goiter occurs more often in patients with primary compared to those with secondary amyloidosis [ 11 ].…”