FDG PET/CT Findings of Rapidly Progressive Interstitial Lung Disease in a Patient With Anti-MDA5 Dermatomyositis.

ABSTRACT: Anti-MDA5 dermatomyositis is associated with an increased risk of developing rapidly progressive interstitial lung disease with a high mortality. We describe FDG PET/CT findings in a case of rapidly progressive noninfectious interstitial lung disease associated with anti-MDA5 dermatomyositis. The lung disease showed bilateral diffuse ground-glass opacities with diffuse heterogeneous FDG activity predominantly in middle and lower zones, mimicking infectious pneumonia. Familiarity with the imaging features of this rapidly progressive noninfectious interstitial lung disease can help to suggest the diagnosis and guide appropriate management.

FDG PET/CT in Staging of α-Fetoprotein-Producing Hepatoid Adenocarcinoma of the Pancreas.

ABSTRACT: Hepatoid adenocarcinoma of the pancreas is a rare aggressive tumor with poor prognosis. We describe contrast-enhanced CT and FDG PET/CT findings in a case of pancreatic hepatoid adenocarcinoma with significantly elevated α-fetoprotein level presenting as acute pancreatitis. The primary pancreatic tumor diffusely involved the pancreas and showed heterogeneous enhancement mimicking acute necrotizing pancreatitis on contrast-enhanced CT. FDG PET/CT showed intense FDG uptake (SUVmax, 24.5) of the left supraclavicular and retroperitoneal lymph node metastases, suggesting FDG PET/CT may be useful for staging of this aggressive tumor.

FDG PET/MRI in a Case of Isolated Abdominal Incisional Site Metastasis After Laparoscopic Surgery for Colon Cancer.

ABSTRACT: Abdominal-wall metastasis following laparoscopic surgery for colorectal cancer is rare. We describe FDG PET/MRI findings in a case of isolated abdominal incisional site metastasis after laparoscopic surgery for colon cancer. The abdominal-wall metastasis showed slight hyperintensity on T2-weighted fat-suppressed image and intense focal FDG uptake on PET. This case demonstrates the usefulness of FDG PET/MRI in detecting the atypical metastasis from colon cancer.

Thoracic SMARCA4-Deficient Undifferentiated Tumor Mimicking Malignant Pleural Mesothelioma on FDG PET/CT.

ABSTRACT: We describe contrast-enhanced CT and FDG PET/CT findings in a case of thoracic SMARCA4-deficient undifferentiated tumor with extensive pleural involvement and mediastinal lymph node metastases. Contrast-enhanced CT showed multiple enhancing right-sided pleural masses and soft tissue plaques and enlarged mediastinal lymph nodes. The pleural lesions and mediastinal lymph nodes showed intense FDG uptake mimicking malignant pleural mesothelioma with mediastinal lymph node metastases.

FDG PET/CT in Staging and Response Evaluation of Primary Urothelial Carcinoma of the Urethra.

ABSTRACT: Primary urethral urothelial carcinoma is a rare aggressive tumor with a high propensity for local invasion and regional and distal metastases. We describe the usefulness of FDG PET/CT in management of a patient with primary urethral urothelial carcinoma. FDG PET/CT at initial staging showed FDG-avid primary tumor and lymph node metastasis of the left groin, and mild or no activity of the lung metastases due to small size. FDG PET/CT after 4 cycles of chemotherapy showed progression of the primary tumor and lung metastases, partial response of the left inguinal lymphadenopathy, and multiple new sites of FDG-avid metastases.

Atypical Bone Involvement in Erdheim-Chester Disease Showing No or Subtle Structure Changes and Increased Activity on FDG PET/CT.

ABSTRACT: Bones are the most common sites involved in Erdheim-Chester disease. On imaging, the bone involvement in Erdheim-Chester disease typically presents as osteosclerotic lesions, and osteolytic lesions are unusual. Bone lesions showing no or subtle structure changes are rarely reported. We describe FDG PET/CT findings in a case of Erdheim-Chester disease with atypical bone involvement. The bone lesions showed no or subtle structure changes without obvious osteosclerosis or osteolysis on radiographs and CT, and increased FDG activity mimicking lymphoma. Familiarity with these atypical imaging findings of bone involvement in Erdheim-Chester disease is helpful for the diagnosis.

Intraureteral Metastasis From Colon Cancer Mimicking Primary Ureteral Carcinoma on FDG PET/CT.

ABSTRACT: Hematogenous or lymphatic intraureteral metastasis from distant primary cancer is very rare. We present contrast-enhanced CT and FDG PET/CT findings in a case of intraureteral metastasis from colonic adenocarcinoma 3 years after colectomy. The intraureteral showed moderate enhancement on contrast-enhanced CT and increased FDG uptake on PET/CT mimicking a primary ureteral carcinoma. This case suggests that metastatic tumor of the ureter should be considered in the differential diagnosis in patients with hypermetabolic ureteral lesion and known malignancy.

18 F-FAPI-42 Versus 18 F-FDG PET/MRI in a Case of Primary Peripheral T-Cell Lymphoma of the Skeletal Muscles.

ABSTRACT: Primary skeletal muscle lymphoma is rare. We describe 18 F-FAPI-42 and 18 F-FDG PET/MRI findings in a case of primary peripheral T-cell lymphoma of the skeletal muscles with brain involvement. The multiple skeletal muscle tumors and one larger cerebral tumor showed intense FDG uptake and mild to moderate FAPI uptake. FDG PET was superior to FAPI PET in delineating the muscle tumors because of significantly higher FDG uptake of the muscle tumors than FAPI uptake. FAPI PET was superior to FDG PET in delineating the cerebral lesion because of a very low background FAPI activity in the brain parenchyma.

FDG PET/CT Findings of Primary Pulmonary Choriocarcinoma in a Postmenopausal Woman.

ABSTRACT: Choriocarcinomas usually occur in the genital tracts of reproductive-age women after a gestational event. Primary pulmonary choriocarcinoma is very rare. We describe FDG PET/CT findings of primary pulmonary choriocarcinoma with multiple intrapulmonary metastases in a postmenopausal woman with elevated serum beta human chorionic gonadotropin level. On FDG PET/CT, the large primary lung tumor showed intense FDG uptake (SUV max , 46), and the small intrapulmonary metastases showed variable FDG uptake (SUV max , 27). Primary pulmonary choriocarcinoma should be included in the differential diagnosis of FDG-avid pulmonary lesions with elevated serum beta human chorionic gonadotropin levels, including metastatic choriocarcinoma and lung cancer.

FDG PET/CT in a Case of Solitary Mixed Squamous Cell and Glandular Papilloma of the Lung With High CEA Level.

ABSTRACT: Solitary mixed squamous cell and glandular papilloma of the lung is an extremely rare benign neoplasm. We describe FDG PET/CT findings in a case of solitary mixed squamous cell and glandular papilloma of the lung with high serum carcinoembryonic antigen level (63.3 ng/mL; reference, <5 ng/mL). The tumor showed intense FDG uptake with SUVmax of 23.8 mimicking lung cancer.

Diffuse Intense 18 F-PSMA-1007 Uptake of the Breasts in a Woman With TFE3-Rearranged Renal Cell Carcinoma.

ABSTRACT: A 23-year-old woman presenting with gross hematuria was found to have a left renal mass suspicious for renal cell carcinoma on abdominal contrast-enhanced CT. An 18 F-PSMA-1007 PET/CT scan was performed for evaluating the renal mass. 18 F-PSMA-1007 PET/CT showed focal activity of the renal mass, which was a transcription factor E3-rearranged renal cell carcinoma proved after nephrectomy. Surprisingly, diffuse heterogeneous intense activity of the bilateral breasts and moderate activity of the right accessory breast was observed. There was no morphological abnormality of the bilateral breasts and right accessory breast on CT images, indicating physiological PSMA uptake.

Intense FDG Uptake in Well-Differentiated Inflammatory Liposarcoma of the Retroperitoneum.

ABSTRACT: Inflammatory variant of well-differentiated liposarcoma is a rare subtype of liposarcoma, and its imaging features have been rarely reported. We describe FDG PET/CT findings in a case of well-differentiated inflammatory liposarcoma. The tumor showed no detectable fat and intense FDG uptake and caused diffuse FDG uptake of the bone marrow due to paraneoplastic leukemoid reaction. Microscopically, there were extensive inflammatory infiltrates in the tumor, which may contribute to the intense FDG uptake. This case indicates that although well-differentiated liposarcoma usually shows low-grade FDG uptake, inflammatory variant of well-differentiated liposarcoma can show intense FDG uptake mimicking high-grade liposarcoma.

Juxtaglomerular Cell Tumor Mimicking Renal Cell Carcinoma on 99m Tc-MIBI SPECT/CT.

ABSTRACT: Juxtaglomerular cell tumor or reninoma is an extremely rare, typically benign, renin-secreting tumor of the kidney that causes secondary hypertension. We describe 99m Tc-MIBI SPECT/CT findings in a case of juxtaglomerular cell tumor. The renal tumor showed isodensity and photopenia on 99m Tc-MIBI SPECT/CT. This case indicates that juxtaglomerular cell tumor can appear cold on 99m Tc-MIBI SPECT/CT, mimicking renal cell carcinoma.

Intense PSMA Uptake in Solitary Fibrous Tumor of the Seminal Vesicle.

ABSTRACT: Solitary fibrous tumor arising from the seminal vesicle is very rare. We describe 18 F-PSMA-1007 PET/CT findings in a case of prostate adenocarcinoma with a solitary fibrous tumor of the left seminal vesicle. The solitary fibrous tumor showed intense 18 F-PSMA-1007 uptake mimicking metastatic prostate adenocarcinoma. This case indicates that solitary fibrous tumor may cause false-positive result when using PSMA PET in staging of prostate cancer.

Hemangioma of the Ilium Simulating Bone Metastasis on 18 F-PSMA-1007 PET/CT.

ABSTRACT: A 64-year-old man was referred for 18 F-PSMA-1007 PET/CT scan for initial staging of biopsy-proved prostate adenocarcinoma. 18 F-PSMA-1007 PET/CT showed focal intense 18 F-PSMA-1007 of the prostate adenocarcinoma and a focal intense activity with SUV max of 10.5 in the left ilium. The 18 F-PSMA-1007-avid iliac bone lesion corresponded to a hemangioma, which was initially detected on pelvic MRI 13 months ago and remained stable in size. This case indicates that hemangioma should be included in the differential diagnosis of PSMA-avid iliac bone lesions.

FDG PET/CT in a Case of Isolated Gastric Metastasis From Pancreatic Ductal Adenocarcinoma.

ABSTRACT: Hematogenous gastric metastasis from pancreatic cancer is extremely rare. We describe FDG PET/CT findings in a case of isolated hematogenous gastric metastasis from pancreatic cancer with significantly elevated serum carbohydrate antigen 19-9 level. The gastric metastasis showed intense focal FDG uptake mimicking a primary tumor. The elevation of serum carbohydrate antigen 19-9 level may be useful as an aid in the differential diagnosis.

Intense FDG Uptake in Leiomyomatosis Peritonealis Disseminata With Fumarate Hydratase Deficiency.

ABSTRACT: A 35-year-old woman with a history of laparoscopic myomectomy presented with repeated abdominal pain. Contrast-enhanced abdominal and pelvic CT showed multiple enhancing solid or mixed cystic and solid peritoneal masses, and an enhancing uterine mass. All these masses showed intense FDG uptake on FDG PET/CT. The intraperitoneal and uterine masses were surgically removed. The histological and immunohistochemical findings of the peritoneal lesions were consistent with leiomyomatosis peritonealis disseminata with fumarate hydratase deficiency, and the uterine mass was adenomyosis. This case indicates fumarate hydratase-deficient extrauterine leiomyoma can show intense FDG uptake mimicking malignancy.

18 F-FAPI-04 PET/CT in a Case of Primary Gastric Plasmacytoma.

ABSTRACT: Primary plasmacytoma of the stomach is very rare. We describe contrast-enhanced CT and 18 F-FAPI-04 PET/CT findings in a patient with primary gastric plasmacytoma and Helicobacter pylori infection. The gastric tumor appeared as a large hypervascular polypoid mass on contrast-enhanced CT and showed intense 18 F-FAPI-04 uptake with SUV max of 11.8 on 18 F-FAPI-04 PET/CT.

FDG PET/CT in a Case of Primary Lymphoma of the Ureter.

ABSTRACT: Primary lymphoma of the ureter is extremely rare. We describe the contrast-enhanced CT and FDG PET/CT findings in a case of diffuse large B-cell lymphoma transformed from mucosa-associated lymphoid tissue lymphoma limited to the left ureter. Contrast-enhanced CT showed 2 short-segment circumferential thickening and enhancement of the left pelvic and intramural ureteral wall. The thickened ureteral wall showed significantly increased FDG uptake mimicking urothelial carcinoma.

Microcystic Serous Cystadenoma Masquerading as Pancreatic Neuroendocrine Tumor on 99m Tc-HYNIC-TOC SPECT/CT.

ABSTRACT: We present 99m Tc-HYNIC-TOC SPECT/CT findings in a case of microcystic serous cystadenoma of the pancreatic head. The pancreatic tumor showed intense 99m Tc-HYNIC-TOC uptake mimicking neuroendocrine tumor on SPECT/CT. This case indicates that microcystic serous cystadenoma should be included in the differential diagnosis of 99m Tc-HYNIC-TOC-avid pancreatic masses.