Secondary Hyperparathyroidism With “Superscan-Like” Hypermetabolic FDG PET/CT Pattern

Case report: 18F-FDG PET/CT skeletal superscan-like in an adult patient with acute lymphoblastic leukemia

We herein describe a rare case of adult acute lymphoblastic leukemia with an 18florine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) skeletal superscan-like appearance. The degree of bone marrow uptake was so intense that it far exceeded the level of physiological cerebral uptake and radiourinary activity. The distribution was remarkably similar to a superscan seen on skeletal scintigraphy. Skeletal superscans of 18F-FDG PET/CT have been reported in hematological diseases, solid tumors with extensive bone metastasis, and metabolic diseases. Thus, we reviewed the PET/CT images of cases reported, indicating that more homogeneous distribution, without primary tumor and specific mandibular and skull activity, may be suggestive of hematological diseases.

Metabolic Superscan on 18 F-FDG PET/CT in a Patient With Secondary Hyperparathyroidism

ABSTRACT

Superscan on PET/CT has been reported in the literature and mainly involved metastatic diseases. We report an uncommon case of a metabolic superscan on 18 F-FDG PET/CT in a 56-year-old man with end-stage renal disease on hemodialysis who presented with secondary hyperparathyroidism. Parathyroid scintigraphy showed 2 lesions posteroinferior to both thyroid lobes, suggestive of parathyroid adenoma/hyperplasia. FDG PET/CT performed to assess for pulmonary nodules revealed diffuse FDG hypermetabolism involving the visualized skull, mandible, spine, sternum, ribs, and appendicular skeleton without corresponding CT lesion with no urinary radiotracer excretion, consistent with metabolic superscan secondary to renal osteodystrophy.

Superscan Appearance of 68Ga PSMA PET/CT in a Patient with Refractory Prostate Cancer

A 64-year-old male patient with metastatic prostate carcinoma diagnosis received lutetium-177 prostate-specific membrane antigen (PSMA) treatment; however, his disease progressed. Herein, presented the final images of the patient that demonstrated a superscan appearance in the Gallium-68 PSMA positron emission tomography/computed tomography, which is a rare phenomenon.

18F-FDG PET/CT Findings in a Patient With Neutrophilic Leukemoid Reaction Associated With Multiple Myeloma

F-FDG PET/CT was performed on a 48-year-old woman with leukocytosis (white blood cell count 57.10 × 10/L, 84.0% neutrophils) and monoclonal gammopathy to investigate the possibility of reactive neutrophilia secondary to plasmacytoma. On the background of skeletal "superscan," the maximum intensity projection image of PET demonstrated the highest metabolic region in the left sacrum, which was confirmed as an osteolytic lesion by CT. Biopsy of the sacral lesion revealed a plasma cell myeloma, indicating the diagnosis of neutrophilic leukemoid reaction associated with multiple myeloma. The white blood cell counts dramatically dropped to the normal level after 1 cycle of chemotherapy for multiple myeloma.

Avid 18F-FDG Uptake in Idiopathic Tumoral Calcinosis Mimicking Lymph Node Metastasis

Tumoral calcinosis is a benign condition characterized by periarticular calcified lesions that is frequently observed in patients with chronic renal failure. Tumoral calcinosis often presents with subcutaneous masses and joint swelling. We present a case of tumoral calcinosis with dramatically increased ¹⁸F-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) that mimicked lymphoma or lymph node metastases.

Clinical Pearls: Etiologies of Superscan Appearance on Fluorine-18-Fludeoxyglucose Positron Emission Tomography-Computed Tomography

The term "superscan" usually refers to a characteristic pattern on skeletal scintigraphy consisting of symmetrically intense and diffuse radiotracer uptake in the skeleton with absent or diminished visualization of the genitourinary system and soft tissues. Superscans and superscan-like appearances have also been described on fluorine-18-fludeoxyglucose positron emission tomography-computed tomography (18-F-FDG PET/CT). We review reported cases of 18-F-FDG PET/CT superscans and propose criteria for differentiating pathologic superscans from physiologic causes. Knowledge of the 18-F-FDG PET/CT superscan, its reported pathologic causes, its benign imitators, and its clinical implications is important to the nuclear medicine physician or radiologist specializing in the interpretation of nuclear studies to avoid several diagnostic pitfalls.