Challenges of Differential Diagnosis Between Primary Hyperparathyroidism and Bone Metastases of Breast Cancer

Abstract

Breast cancer might be complicated by distant metastases accompanied by hypercalcemia, but hyperparathyroidism is not commonly considered in the differential diagnosis. We present a case of 38 years old female patient who was diagnosed with ductal breast carcinoma. Eight months after the initial diagnosis the patient was diagnosed with distant bone metastases. However, this diagnosis was reconsidered at follow up, because we identified elevation of PTH 137.2 pg/ml, Ca²⁺ 1.19 mmol/l, albumin corrected calcium 2.42 mmol/l, 25(OH)D 39.4 nmol/l, indicating hyperparathyroidism. Scintigraphy with 99mTC-sestamibi confirmed parathyroid adenoma. Postoperative histopathology confirmed 1.2 g chief-cell PTA. Two months after the operation both PTH and Ca²⁺ levels were within the normal ranges. This study emphasizes the importance of considering possible hyperparathyroidism in patients with breast cancer and hypercalcemia. Routine evaluation of PTH is considered as a reasonable test in patients with breast cancer accompanied by bone lesions.

Keywords: Diagnosis; bone demineralization; bone diseases; breast; carcinoma; differential; ductal; endocrine; hyperparathyroidism; pathologic; primary.

Figure 1.

Comparison of the whole body bone scintigraphy with technetium 99m-methyl diphosphonate before and after removal of parathyroid adenoma (View 1—anterior view of the skeleton, View 2—posterior view of the skeleton). (A) Scintigraphy was performed at baseline showing hyperfixation of radiotracer in the thoracic and lumbar spine bones, ribs, as well as in the right ileum bone. (B) At follow up (3 months after removal of parathyroid adenoma) scintigraphy showed decreasing number of bone lesions as well as decreasing of radiotracer uptake as compared to baseline.

Figure 2.

Photograph of whole-body CT scan showing a well-circumscribed mixed density nodule posterior to the left thyroid lobe (the locations of the nodule are marked by arrows ). This lesion is separated by a thin tissue plane from the adjacent anatomical structures, including the left thyroid lobe ((A)—sagittal plane; (B)—coronal plane; (C)—axial plane).

Figure 3.

Ultrasonography illustration of the left parathyroid gland 4.5 × 4.5 mm in the largest diameter (marked with the rectangle).

Figure 4.

Photograph of scintigraphy with 99mTC-sestamibi showing a clear focus of strong signal from the radiotracer in the area of the lower pole of the left thyroid lobe (indicated by the dotted ellipse).

Figure 5.

(A) Macrophotograph of the removed parathyroid adenoma of the left upper parathyroid gland under the room light. Photograph of the right parathyroid adenomas showing autofluorescence in near-infrared light. (B) Photograph of the parathyroid adenoma exhibiting autofluorescence signal in near-infrared light (marked with the dotted ellipse).