Penile metastasis from prostate adenocarcinoma is an exceptionally rare manifestation of advanced disease. We report the case of a 64-year-old man with biopsy-proven prostatic adenocarcinoma (cT3bN1M1, Gleason 4+4=8), diagnosed in 2020 with an initial PSA of 122.85 ng/mL. The most remarkable finding was intense, diffuse, and homogeneous PSMA uptake throughout the corpora cavernosa along the entire penile shaft (SUVmax=76.9). Histopathologic examination confirmed metastatic prostatic adenocarcinoma (Grade Group 3, Gleason 4+3=7), involving 100% of the sampled penile tissue. This case illustrates an unusual pattern of diffuse penile involvement, likely reflecting advanced hematogenous or retrograde venous dissemination rather than focal metastatic deposits. It underscores the importance of careful evaluation of the external genitalia on PSMA PET/CT and highlights that penile metastases may present as diffuse, highly PSMA-avid infiltration in advanced prostate cancer.
The management of differentiated thyroid cancer (DTC) has undergone a major paradigm shift over the past decade, with increasing emphasis on treatment de-escalation and avoidance of overtreatment in patients with low-risk disease. The 2015 American Thyroid Association guidelines marked a turning point by discouraging routine postoperative radioiodine (RAI) remnant ablation in low-risk patients, reflecting the excellent prognosis of most papillary thyroid carcinomas and concerns regarding unnecessary therapy-related morbidity. The rising incidence of thyroid cancer, largely due to increased detection of indolent tumors without any rise in mortality, further reinforced a more conservative approach. Although the toxicities of RAI are generally limited, potential long-term effects have also contributed to a reduction in its use. The recent population-based analysis by Weis and colleagues challenges the simplicity of this universal de-escalation strategy. The authors confirmed the lack of survival benefit from RAI in node-negative papillary thyroid carcinoma. On the contrary, they also identified subgroups who appeared to derive a long-term survival advantage from RAI. These findings highlight the biological heterogeneity of DTC and suggest that treatment decisions should extend beyond conventional low-risk classifications, supporting a more individualized and nuanced approach to postoperative RAI use.
A 60-year-old patient with right temporal glioblastoma (WHO CNS grade 4) underwent resection and chemoradiation. Seven-month follow-up MRI showed new contrast enhancement at the resection margin. To distinguish tumor recurrence from treatment-related changes, [18F]FET-PET/MRI was performed. Intense [18F]FET tracer accumulation in the contrast-enhancing right temporal lesion suggested tumor recurrence (TBRmax: 2.8; TBRmean: 1.9). A second focal [18F]FET-uptake in the right cerebellum (TBRmax: 2.3; TBRmean: 1.7) corresponded to a "Medusa head" venous pattern on MRI. This finding is consistent with a developmental venous anomaly (DVA). Correlation of [18F]FET-uptake with MRI features is essential to avoid diagnostic pitfalls, such as DVAs.
False-positive findings on molecular imaging can pose significant diagnostic dilemmas in oncological cases. We report an elderly woman with metastatic neuroendocrine tumor of unknown primary who underwent 5 cycles of [177Lu]Lu-DOTATATE PRRT and achieved a partial response. On follow-up, [68Ga]Ga-DOTATATE and [18F]FDG-PET/CT scans demonstrated a new-onset FDG avid-hypermetabolic, low-grade SSTR-expressing cervical lymph node chain extending into the mediastinum, raising concern for disease progression or a second malignancy. Histopathology of the lymph nodes revealed granulomatous inflammation consistent with tuberculosis. This case highlights tuberculosis as a potential cause of false-positive dual-tracer PET positivity and the need for histologic confirmation before changing the management.
A 62-year-old man with newly diagnosed prostate adenocarcinoma underwent initial staging with 99m Tc-PSMA and 99m Tc-MDP whole-body scans. The bone scan revealed a small zone of tracer activity superior to the left kidney. Subsequent 99m Tc-PSMA SPECT/CT revealed a fluid density collection in the left perinephric and pararenal space, extending from the left subdiaphragmatic area to the pelvic inlet. PSMA tracer activity was seen around the left kidney. Contrast-enhanced CT confirmed a perinephric fluid collection consistent with urinoma. This case underscores the importance of recognizing atypical patterns of 99m Tc-PSMA uptake to improve diagnostic accuracy, avoid misinterpretation, and ensure appropriate patient management.
False-positive findings on molecular imaging can pose significant diagnostic dilemmas in oncological cases. We report an elderly woman with metastatic neuroendocrine tumor of unknown primary who underwent 5 cycles of [ 177 Lu]Lu-DOTATATE PRRT and achieved a partial response. On follow-up, [ 68 Ga]Ga-DOTATATE and [ 18 F]FDG-PET/CT scans demonstrated a new-onset FDG avid-hypermetabolic, low-grade SSTR-expressing cervical lymph node chain extending into the mediastinum, raising concern for disease progression or a second malignancy. Histopathology of the lymph nodes revealed granulomatous inflammation consistent with tuberculosis. This case highlights tuberculosis as a potential cause of false-positive dual-tracer PET positivity and the need for histologic confirmation before changing the management.
An 80-year-old man underwent 18 F-FDG PET/CT and 68 Ga-FAPI PET/CT for a biopsy-confirmed metastatic gastrointestinal stromal tumor (GIST). While 18 F-FDG PET/CT revealed intensely increased uptake in the perisplenic, right abdominal, and pelvic peritoneal implants, 68 Ga-FAPI PET/CT unexpectedly showed negligible tracer uptake across all corresponding lesions.
Primary extraosseous Ewing sarcoma located in the abdominal cavity and retroperitoneum is rare. We report the 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT imaging findings of intra-abdominal Ewing sarcoma. The mass showed mild FDG uptake and avid FAPI uptake.
A 60-year-old patient with right temporal glioblastoma (WHO CNS grade 4) underwent resection and chemoradiation. Seven-month follow-up MRI showed new contrast enhancement at the resection margin. To distinguish tumor recurrence from treatment-related changes, [ 18 F]FET-PET/MRI was performed. Intense [ 18 F]FET tracer accumulation in the contrast-enhancing right temporal lesion suggested tumor recurrence (TBRmax: 2.8; TBRmean: 1.9). A second focal [ 18 F]FET-uptake in the right cerebellum (TBRmax: 2.3; TBRmean: 1.7) corresponded to a “Medusa head” venous pattern on MRI. This finding is consistent with a developmental venous anomaly (DVA). Correlation of [ 18 F]FET-uptake with MRI features is essential to avoid diagnostic pitfalls, such as DVAs.
Hyperpolarized [1- 13 C]pyruvate MRI enables real-time assessment of tumor glycolytic flux. We report 2 women with suspected ovarian cancer examined preoperatively with hyperpolarized [1- 13 C]-pyruvate MRI and FDG PET/CT. In a 49-year-old woman with a right adnexal mass, FDG uptake was limited, and hyperpolarized imaging demonstrated minimal lactate production; histopathology revealed a benign fibroma. In a 51-year-old woman with advanced disease, FDG PET/CT showed extensive metabolically active tumors. Hyperpolarized imaging demonstrated markedly increased lactate-to-pyruvate conversion within solid tumor components. Histopathology confirmed high-grade serous carcinoma. These cases illustrate the potential complementary role of hyperpolarized [1- 13 C]pyruvate MRI in differentiating benign from malignant adnexal masses.
Scintigraphy using 99m Tc-PYP as a bone-avid radiotracer reveals physiological and pathologic accumulation of the tracer in the extraosseous tissues and organs—including the breasts—in addition to the bones. 99m Tc-PYP scintigraphy also reveals deposits of wild-type amyloid transthyretin (ATTRwt) in the myocardium and extracardiac sites, such as subcutaneous fat, skeletal trunk muscles, and alimentary tract, of patients with ATTRwt cardiomyopathy (CM). We describe an 87-year-old man with ATTRwt-CM in whom myocardial 99m Tc-PYP uptake was reduced and mammary tracer uptake was increased due to gynecomastia after treatment with a disease-modifying drug for ATTRwt-CM, tafamidis, and heart failure medications, including spironolactone.
A 68-year-old man with metastatic prostate adenocarcinoma was treated with androgen-deprivation therapy and chemotherapy. Restaging 68 Ga-PSMA PET/CT revealed a PSMA-avid lesion in the left temporal lobe, which was treated with brain radiotherapy. Subsequent PSMA PET/CT showed brain lesion progression and skeletal metastases. He underwent brain lesion resection followed by 4 cycles of 177 Lu-PSMA-617, achieving near-complete resolution of skeletal metastasis. This case highlights the importance of multimodal treatment, including 177 Lu-PSMA, in managing brain metastasis in prostate cancer.
A 23-year-old man with metastatic extraskeletal Ewing sarcoma, who was unable to tolerate standard-dose chemotherapy, received 1 cycle of 177 Lu-FAP-2286, followed by 2 cycles of reduced-dose ifosfamide/epirubicin/mesna chemotherapy. Follow-up 68 Ga-FAP-2286 PET/CT at 2 months showed a marked metabolic response with reduced tumor size and tracer uptake. No adverse events were observed. The patient remained symptom-free at 2 months. This case suggests that 177 Lu-FAP-2286 combined with chemotherapy may have clinical utility in advanced Ewing sarcoma.
We report the case of a 58-year-old man with metastatic epithelioid sarcoma demonstrating an uncommon presentation of expanding tumor volume accompanied by a paradoxically lower SUVmax on 18F-FDG PET/CT. Conversely, 68Ga-FAPI PET/CT demonstrated clear diagnostic superiority, exhibiting intense tracer avidity across established lesions and successfully uncovering multiple new, FDG-occult metastases. This distinct metabolic dissociation highlights a stromal-driven mechanism of tumor invasion. Ultimately, 68Ga-FAPI PET/CT significantly outperforms conventional FDG imaging in delineating total disease burden and detecting clinically occult metastases in this aggressive malignancy.
Hibernomas are rare benign tumors derived from brown adipose tissue that may mimic malignancy on imaging. We report a 21-year-old woman with multiple endocrine neoplasia type 1 (MEN1) undergoing serial somatostatin receptor (SSTR) PET imaging after curative treatment for a pancreatic neoplasia in complete remission. An intramuscular lesion showed moderate SSTR expression and slow progressive growth. MRI demonstrated heterogeneous enhancement and diffusion restriction, raising concern for malignancy. Histopathology after biopsy confirmed hibernoma. This case highlights hibernoma as a potential pitfall in SSTR-targeted PET imaging, particularly in MEN1, and underscores the importance of multimodality imaging and histopathologic correlation for accurate diagnosis.
A 41-year-old man with grade 1, well-differentiated neuroendocrine tumor (NET) of the terminal ileum underwent initial staging with 68Ga-DOTATATE PET/CT. PET/CT images demonstrated focal uptake at the terminal ileum corresponding to the patient's known NET. In addition, a large, low-attenuation lesion with heterogeneously increased activity was seen in the interpolar region of the right kidney. Further evaluation with contrast-enhanced MRI demonstrated a finding consistent with a large calyceal diverticulum. PET/CT images were revisited, and the activity in the mass was compared with the activity in the bladder, which was similar.
A 77-year-old man was referred for an 18F-DCFPyl PET/CT scan for staging of prostate cancer. The scan demonstrated an incidental intensely avid brain lesion in the right frontal lobe. Subsequently, a right frontal craniotomy and resection of the lesion were performed, confirming IDH wild-type glioblastoma WHO Grade 4.
A 60-year-old man with signet-ring-component poorly differentiated rectal adenocarcinoma (pMMR, HER2-negative, KRAS/NRAS/BRAF wild-type) received total neoadjuvant therapy, low anterior resection, and adjuvant CAPOX. During biochemical progression (CEA 7.85 → 171.0 µg/L over ∼4 mo), 18F-DG PET/CT showed postoperative/anastomotic uptake (SUVmax 8.5) without definite peritoneal-serosal disease. 68Ga-FAPI-04 PET/CT performed 38 days later demonstrated intense uptake in peritoneal-serosal and mesenteric implants (SUVmax 51.2), the anastomotic and colostomy-site regions (SUVmax 9.3), and a Couinaud segment VI hepatic lesion (SUVmax 6.3). The case illustrates the complementary value of 68Ga-FAPI-04 PET/CT in suspected stromal-rich peritoneal recurrence in a sequential imaging setting.
A 21-year-old man presented with 1-month intermittent abdominal pain and distension. Contrast-enhanced CT and 18 F-FDG PET/CT demonstrated diffuse peritoneal thickening and multiple hypermetabolic masses, initially raising suspicion for malignant disease. Biopsy showed nests of small round blue cells within a desmoplastic stroma. Fluorescence in situ hybridization (FISH) confirmed EWSR1‑WT1 gene fusion, establishing the diagnosis of desmoplastic small round cell tumor (DSRCT). This case highlights that DSRCT should be considered in young men with extensive peritoneal involvement, and that molecular confirmation is essential to avoid diagnostic delay.
