Rare Undiagnosed Primary Amyloidosis Unmasked During Surgical Treatment of Primary Hyperparathyroidism: A Case Report

Primary amyloidosis (PA) is a protein deposition disorder that presents with localized or multisystemic disease. The incidence is low in the general public, ranging from three to eight cases per million, and with nonspecific presenting symptoms typically occurring later in life. Due to late presentation, substantial and irreversible damage has usually already occurred by the time of the diagnosis. However, if inadvertent diagnosis occurs before irreversible damage has taken place, as it did in the following case, some patients may benefit from the disease-arresting treatment. A 70-year-old female with a history of obstructive sleep apnea, hypertension, and arthritis presented with worsening dysphagia and biochemically confirmed primary hyperparathyroidism (PHPT). Further workup demonstrated multinodular goiter with compressive symptoms and substernal extension, osteopenia, and discrepant parathyroid localization on imaging. Intraoperatively, markedly difficult dissection and obliteration of tissue planes were encountered. Extensive, diffuse amyloid deposition in both the normal and pathologic parathyroid glands and thyroid tissue on surgical pathology leads to subsequent fibril typing by mass spectrometry and leads to the diagnostic of primary amyloid light-chain (AL) amyloidosis (PA; λ light chains). Subsequent workup for the underlying cause of the amyloid deposition revealed an immunoglobulin A monoclonal gammopathy of unknown significance. The surgical treatment of PHPT and compressive thyroid nodule unmasked an undiagnosed PA, allowing for early workup and monitoring of the progression of amyloidosis. The temporal comorbidity of PHPT and PA raises an interesting and, as yet, unanswered question regarding the pathophysiologic association between the two conditions.