case_images: PMC9792501_01
case_images: Details of patient surgeries during the course of the disease.
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case_images: In the last 16 years, the patient has undergone neck (exploration) surgery four times, however, PHPT has not been cured ( Figure 1 ). Figure 2 ) The lower right parathyroid gland was excised, and the left thyroid lobectomy was performed without any early complications. Following surgery, serum calcium levels were corrected, while iPTH levels declined dramatically without being in the normal range ( Figure 1 ). She underwent a second neck exploration due to elevated serum iPTH and calcium levels and increased uptake in the left upper side of the neck on the 99mTc Sestamibi (MIBI) scan ( Figure 1 ). Subsequent parathyroid surgery was performed a year later, following impaired iPTH and calcium and hyperfunction parathyroid tissue in the left upper portion of the thyroid lobe in the MIBI scan accompanied by findings of parathyroid adenoma in single-photon emission computed tomography/CT (SPECT/CT) scan ( Figure 1 ).
case_images: Serial serum levels of calcium and iPTH among clinical events. The dotted lines represent the reference lines.
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case_images: Figure 2 ) The lower right parathyroid gland was excised, and the left thyroid lobectomy was performed without any early complications. Following surgery, serum calcium levels were corrected, while iPTH levels declined dramatically without being in the normal range ( Figure 1 ). Intact PTH levels remained high in all subsequent postoperative visits ( Figure 2 ).
case_images: The ectopic parathyroid adenoma in the right lower lobe was demonstrated in (A)
  99mTc Sestamibi scan, (B) 18F-FDG PET scan.
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case_images: The SPECT-CT scan showed nothing suggestive of parathyroid adenoma, neither in the neck nor in the mediastinum, but a solitary MIBI avid nodule was reported in the lower lobe of the right lung (11 x 5 mm) and was proposed to be ruled out for malignancy ( Figure 3A ). In fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET), a faintly FDG-avid solid pulmonary nodule with a maximum standardized uptake value of 1.6 was noted in the right lower lobe. ( Figure 3B ).
case_images: The pathological specimen confirms that parathyroid chief cells arrange in the adenoma tissues. (A) presence of well-defined nodule in lung parenchyma; (B, C) Monotonous population of cells with round nuclei, salt and pepper chromatin devoid of mitotic figures; (D) PTH cytoplasmic immunostaining.
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case_images: Pathological examination of the nodule which was 4 mm in the greatest dimension, confirmed the presence of parathyroid adenoma and a positive IHC staining for iPTH ( Figure 4 ).