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Case presentation

A fifty-five year old Caucasian male presented with a swelling in the left neck that was increasing in size as well as complaints of recurrent dysphonia. Laboratory investigation demonstrated a calcium level of 11.1 mg/dL, a parathyroid hormone (PTH) of 467 pg/mL, and he was subsequently referred to otolaryngology for management of primary hyperparathyroidism. Physical examination revealed a palpable left paratracheal mass without associated lymphadenopathy. A fiberoptic laryngoscopy demonstrated decreased motion of the left vocal cord and ultrasound showed a 4 cm left-sided nodule. The fine needle aspiration (FNA) was compatible with nodular goiter. Technetium-99 m sestamibi parathyroid scan demonstrated inferior right-sided uptake suggestive of adenoma ( Fig. 1 A ). Parathyroidectomy was recommended. Four days before surgery, the patient’s calcium levels spontaneously dropped to 8.3 mg/dL. The patient underwent parathyroid exploration during which the right side was found to be negative for abnormal parathyroid tissue. On the left, a large, adherent mass contiguous with the thyroid gland and engulfing the left recurrent laryngeal nerve was found. Left hemithyroidectomy was done due to concern for malignancy. Pathologic examination was performed ( Fig. 1 B–D) and the diagnosis of parathyroid adenoma with infarction was made.

Imaging and histologic results of parathyroid studies.

(A) Delayed 2 h images residual radiotracer uptake is seen within the right inferior thyroid bed consistent with a right inferior parathyroid adenoma. (Planar imaging and tomography (SPECT) of parathyroid glands using an intravenous dose of 24.0 mCi of Tc-99 m sestamibi). (B) This section shows a rim of parathyroid tissue in the upper portion of the image with extensive central infarction seen in the lower portion of the image (H&E stain, 40 ×). (C) On higher power, the image consists almost entirely of infarcted parathyroid gland with a small focus of residual parathyroid gland (upper left) (H&E stain, 100 ×). (D) Immunostain for PTH shows strong cytoplasmic staining, confirming parathyroid origin (PTH immunostain, 200 ×).

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Discussion

Pathologic analysis of the specimen revealed an enlarged (7.0 cm in greatest dimension) left parathyroid gland. The parathyroid tissue was densely adherent to the left lobe of the thyroid gland. Cytologic sections showed hypercellular parathyroid tissue with extensive coagulative necrosis, hemorrhage, and granulation tissue ( Fig. 1 B and C). The thyroid tissue was consistent with multinodular goiter and was positive for thyroid transcription factor 1 (TTF-1) and thyroglobulin. Scant residual hypercellular parathyroid tissue was found and demonstrated positive immunohistochemical staining for PTH ( Fig. 1 D). Immunostaining for Ki-67 revealed a low mitotic index with relatively higher mitotic rates in the areas of infarction. No definitive evidence of malignancy was identified. A diagnosis of parathyroid adenoma infarction (PAI) was made. The patient recovered, was discharged home, and demonstrated PTH of 94 pg/mL and calcium of 9 mg/dL at one month postop. Residual left vocal cord paralysis was rehabilitated with medialization laryngoplasty.

Parathyroid adenomas account for 85% of primary hyperparathyroidism (PHPT), a condition characterized by autonomous PTH production resulting in hypercalcemia . PAI is a rare phenomenon being was first reported in 1946 . Spontaneous remission of PHPT secondary to parathyroiditis, hemorrhage, or infarct has been reported, with PAI having a clinical course similar to that of pituitary apoplexy . PAI presentation depends on the severity of the infarct, ranging from a brief respite of symptoms in a mild infarct to complete resolution of disease with or without acute hypocalcemia in more severe cases . Rarely, hemorrhage of the adenoma into the mediastinum may occur resulting in a surgical emergency . The majority of cases present with a sharp, unexpected drop in calcium levels, a transient period of normocalcemia and resolution of symptoms, then ultimately disease recurrence, which has been reported up to three years following infarct. Symptoms of PAI include gastrointestinal discomfort, tetany, convulsion, and cervical pain, while severe hemorrhagic cases demonstrate additional dysphagia, dysphonia, widened mediastinum, and ecchymosis . The involvement of the recurrent laryngeal nerve (RLN) by a parathyroid adenoma and PAI, as seen in this patient, is rarely reported . In contrast to our case, the parathyroid tissue is often nonadherent to the nerve, and its surgical removal results in resolution of hoarseness. In our patient, the Technetium-99 m sestamibi scan was notably negative on the left side on the same day the calcium was found to have decreased to 8.3 mg/dL, four days prior to scheduled operation. Our patient did not demonstrate tetany, hyperreflexia, psychiatric changes, cervical neck pain, or spasms on preoperative examination despite the nearly 3 mg drop in calcium concentration.