A Case of Brown Tumor on 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT

Differentiating Brown Tumor From Bone Metastasis in Parathyroid Cancer Using 18 F-FDG PET and 99m Tc-MIBI SPECT

ABSTRACT

A 69-year-old woman presented with a right clavicle pain. CT revealed a pathological fracture of the right clavicle, multiple osteolytic lesions, and a left cervical mass. 18 F-FDG PET/CT demonstrated a marked FDG uptake in the cervical mass and osteolytic lesions indicative of metastatic parathyroid cancer. 99m Tc-MIBI SPECT/CT revealed either faint or no uptake in the osteolytic lesions. However, a histopathological analysis after a parathyroidectomy and right clavicle biopsy confirmed the diagnosis of parathyroid cancer and the presence of benign brown tumors secondary to hyperparathyroidism. Postoperative imaging showed sclerotic change and a decreased FDG uptake in the bone lesions.

Synchronous Endometrial Cancer Detected on 68 Ga-DOTATATE PET/CT

ABSTRACT

A 50-year-old woman with history of metastatic neuroendocrine tumor underwent a follow-up PET/CT with 68 Ga-DOTATATE. An enlarged uterus with diffuse increased uptake warranted further investigation with an MRI that showed mass-like thickening of the endometrium, T2 hyperintensity, lobulated contour, and invasion of more than 50% of the myometrium. Biopsy revealed endometrial carcinoma with mucinous features. Mild to moderate uptake of the 68 Ga-DOTATATE by the uterus can be a normal physiological finding; however, it should prompt further investigation, particularly in a postmenopausal woman with concerning imaging or clinical findings.

Increased Uptake of Brown Tumor in 99m Tc-HYNIC-TOC Scintigraphy Mimicking Postoperative Recurrence of Tumor-Induced Osteomalacia

ABSTRACT

A 61-year-old man underwent a resection of tumor in the left tibia that caused osteomalacia 11 years ago. Postoperative bone pain and fatigue symptoms were briefly relieved but then recurred. To identify potential recurrent tumors, 99m Tc-HYNIC-TOC scintigraphy was performed. Images revealed an osteolytic lesion in the right tibia with increased uptake. The lesion was subsequently resected, which pathologically proved a brown tumor. Symptoms of bone pain and weakness caused by osteomalacia did not relieve 4 months after the operation. Here, we present a rare case of brown tumor with high activity on 99m Tc-HYNIC-TOC SPECT/CT, mimicking a culprit tumor of osteomalacia.

Localization of Brown Tumors With 18F-Fluorocholine PET/CT Imaging in Severe Primary Hyperparathyroidism

ABSTRACT

We present the case of a 68-year-old woman with a painful tibial tumor and fatigue. Histology and laboratory studies were consistent with a brown tumor secondary to initially unrecognized, severe primary hyperparathyroidism. 18F-fluorocholine PET/CT revealed a large hypermetabolic parathyroid mass and multiple bone foci considered as brown tumors. Unilateral neck exploration confirmed a large parathyroid adenoma. Serum calcium and parathyroid hormone levels normalized quickly, and symptoms subsided gradually after parathyroidectomy. Brown tumors are a rare complication of severe hyperparathyroidism. 18F-fluorocholine PET/CT allows the localization of parathyroid adenomas and brown tumors, and can be used as a single imaging modality.

Brown tumors in nuclear medicine: a systematic review

Brown tumors (BT) are abnormal bone-repair processes and a consequence of hyperparathyroidism. The diagnosis of these lytic lesions in nuclear medicine, while a challenge, is not so rare, because functional imaging is used both in the management of cancer and hyperparathyroidism. The main objective of this review is to summarize the knowledge and the evidence concerning BT and the different imaging modalities in nuclear medicine. A systematic review was performed in Embase, PubMed and Google Scholar from 2005 to 2022. We included articles describing BT in the following imaging modalities: [¹⁸F]-fluorodeoxyglucose PET/CT, [¹⁸F]-fluorocholine or [¹¹C]-fluorocholine PET/CT, [^99mTc]-Sestamibi scintigraphy, bone scan, [¹⁸F]-sodium fluoride PET/CT, [⁶⁸Ga]-FAPI PET/CT; [⁶⁸Ga]-DOTATATE PET/CT; [¹¹C]-methionine PET/CT. For each modality, appearance, avidity for radiotracer, available quantitative parameters and imaging evolution after parathyroidectomy were collected and analyzed. Fifty-two articles were included for a total of 392 BT lesions. If the diagnosis of BT is evoked on a known lesion, performing a [¹⁸F]-fluorocholine PET/CT imaging seems the most appropriate. In [¹⁸F]-fluorodeoxyglucose, [¹⁸F]-fluorocholine, [¹⁸F]-sodium fluoride PET/CT and bone scan, BT can mimic metastatic disease. BT uptakes appear reversible after parathyroidectomy, with a more or less rapid decrease depending on the imaging modality used.

Multiple endocrine neoplasia type 1 or 4: detection of hyperfunctioning parathyroid glands with 18F-fluorocholine PET/CT. Illustrative cases and pitfalls

¹⁸F-fluorocholine (FCH) PET/CT is now well established to detect the hyperfunctioning parathyroid glands (HFPTG) in a case of sporadic primary hyperparathyroidism (pHPT), but only limited evidence is available about the utility of FCH PET/CT to detect the HFPTG in patients with multiple endocrine neoplasia (MEN) type 1 or 4. The pHPT in this context frequently consists in a multiglandular disease with small hyperplastic glands rather than adenomas, which is challenging for imaging modalities. The data of patients with MEN1 or MEN4 after parathyroidectomy referred to FCH PET/CT for presurgical localization of HFPTG were retrospectively reviewed, including follow-up after parathyroidectomy, in search for diagnostic performance and for potential pitfalls. In the present cohort, 16 patients referred to FCH PET/CT as part of their initial pHPT work-up were subsequently operated, 44 abnormal parathyroid glands (PT) were resected, of which 32 (73%) had been detected on FCH PET/CT and 2 considered as equivocal foci. Nine patients referred to FCH PET/CT for recurrent pHPT who were subsequently operated, 14 abnormal PT were resected, all had been detected on FCH PET/CT. FCH PET/CT permitted a unilateral approach for PTx in 4 of them. In one patient with MEN4 and pHPT, the HFPTG could not be visualized on FCH PET/CT but was localized by ultrasonography. Several causes of false positive or false negative results, incidental finding and pitfalls are listed and discussed. FCH PET/CT has a positive benefit/risk ratio in the detection of HFPTG in case of MEN1 (the data in MEN4 being currently very limited) with the most effective detection rate of current imaging modalities for HFPTG, few pitfalls, and an adequate impact on patient management compared to sesta MIBI SPECT and ultrasonography.