A young woman of 26 years was admitted to Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, due to a swelling in the left jawbone. An incisional biopsy of the left maxillary lesion was performed, which proved to be suggestive of fibrous-bone lesion due to certain characteristics, including the presence of fibrous struma, immature bone trabeculae and a high proportion of multinucleated giant cells, without atypia. Contextually, a series of blood tests showed an increase in serum levels of PTH (1320.0 pg/ml), alkaline phosphatase (379 U/L), calcium (15.8 mg/dl), a lowering of the vitamin D values (8.8 ng/mL) and phosphorous (2.1 mg/dl). Of note, further laboratory examinations and clinical workup excluded any suspicion of the presence of other malignancies characterized by bone lytic lesions.
The endocrinological consultations raised a diagnostic suspicion of primary hyperparathyroidism with ultrasound and color–power-Doppler evidence of hyperplastic parathyroid tissue in the lower left parathyroid lodge of 33.3 mm × 11.2 mm × 16.6 mm with contextual vascularization (Fig. 1). Parathyroid SPECT imaging was performed after intravenous administration of 296 MBq of [99mTc]Tc-sestamibi and subsequent integration with 185 MBq of 99mTc-perthecnetate. The images were obtained 15 min after tracer injection (early phase) and 180 min after tracer injection (late phase). Early phase showed a focal uptake in the lower left parathyroid lodge, while late phase did not show any wash-out confirming the diagnosis of hyperfunctioning parathyroid tissue in the lower left parathyroid lodge (Fig. 2).
The patient, treated with cinacalcet hydrochloride 30 mg 1 capsule twice daily, was referred to Department of Advanced Biomedical Sciences, University of Naples Federico II to perform [18F]fluorocholine PET/CT before surgical treatment according to EANM guidelines (Petranović Ovčariček et al. 2021) to evaluate the potential presence of ectopic and supernumerary glands in a patient with primary hyperparathyroidism. PET/CT unenhanced scan was acquired using a PET/CT Ingenuity TF (Philips Healthcare, Best, The Netherlands) 5 min and 60 min after administration of 280 MBq of [18F]fluorocholine (activity range 200–300 MBq according to body weight) as previously described (Nappi et al. 2022).
As illustrated in Fig. 3, [18F]fluorocholine PET/CT scan showed focal uptake of the tracer, both in early and late acquisitions, posteriorly to the lower third of the left thyroid lobe, confirming the diagnosis of hyperfunctioning parathyroid tissue demonstrating a maximum standardized uptake value (SUVmax) of 6.3 in the early phase and of 6.0 in the late phase. On the whole-body images, multiple areas of increased tracer uptake were observed on bone compartment, corresponding to skeletal lesions with morpho-structural alteration of the lytic type on co-registered CT. These bone images corresponded to: the left ethmoid labyrinth (SUVmax 7.2), left mandibular arch (SUV max 5.6), mandibular symphysis (SUVmax 7.3), right acromion (SUVmax 6.3), anterolateral side of the V and VII ribs of the right hemithorax (SUVmax 7.0), ileo-pubic branch bilaterally (SUVmax 4.5 on the left, SUVmax 7.9 on the right), the pubic symphysis (SUVmax 8.5 on the left, SUVmax 7.6 on the right), the right ischial bone (SUVmax 7.6) and the medial condyle of the left femur (SUVmax 2.4) (Fig. 4).
The final imaging report confirmed the clinical suspicion of hyperfunctioning parathyroid tissue on lower left parathyroid lodge and also reported the presence of multiple lytic bone lesions avid of [18F]fluorocholine suggesting hyperparathyroidism associated with skeletal involvement (Figs. 5 and 6). Subsequently, the patient underwent, after appropriate surgical consultation, a surgical removal of the lesion of the lower left parathyroid. Pathological examination of the surgical tissue confirmed the presence of hyperplastic parathyroid tissue compatible with parathyroid adenoma.