Case 42
Presentation:
A 59-year-old male presenting with splenic mass with nonspecific appearance in recent MRI. He has history of kidney transplant and query PTLD (Post-transplant lymphoproliferative disorder ) . A scan was performed in nuclear medicine department to r/o hemangioma in the spleen. What is the radiotracer?
Dynamic phase; Anterior and posterior views (displayed in alternate rows):
Blood pool planar images at 15 minutes (Anterior and posterior and oblique views)
3h delayed planar images (Anterior and posterior and oblique views)
Radiotracer: Radiolabled RBC (RBC scan)
TECHNIQUE: The patients blood was withdrawn and labeled with the in-vitro ultra-tag method.
20-25 mCi of Tc99m labelled RBCs were injected intravenously. Dynamic imaging as well as planar images of the abdomen and pelvis were acquired at 15 minutes and 3 hour delay, as wel as SPECT/CT were acquired.
Findings: In dynamic images Homogeneous uptake is noted in the liver, and transplanted kidney (right lower quadrant). A photopenic region is observed overlying the inferior part of the spleen. The 15-minute delayed static imaging shows a photopenic area in the inferior spleen with minimal radiotracer uptake towards the center of the lesion on the 3.5-hour delayed imaging. The SPECT-CT imaging also demonstrates well-defined round shape photopenic hypodense soft tissue mass (maximum diameter measuring 6 cm) in the inferior part of the spleen.
What is your opinion?
The uptake pattern in the hypodense and photopenic splenic lesion is atypical for a hemangioma. Other considerations, such as a lymphoid lesion, should be included in the differential diagnosis, particularly given the patient's history of renal transplantation and immunocompromised status.
Subsequently, an FDG PET scan was performed to evaluate for questionable post-transplant lymphoproliferative disorder (PTLD) following a kidney transplant. Describe the findings:
FDG PET-CT demonstrates intense metabolic activity in the splenic mass (SUVmax : 35 ). There are also Intensely hypermetabolic gastric lesions, and upper abdominal soft tissue lesions along with intra-abdominal and retroperitoneal FDG avid lymph nodes which are compatible with lymphomatous involvement.
The splenic mass was biopsied and confirmed to be consistent with diffuse large B-cell lymphoma (DLBCL).
Discussion:
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In RBC scan, hemangiomas are typically characterized by low perfusion and high blood pool activity, which distinguishes them from other abnormalities. This pattern was not observed in this case.
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On FDG PET, hemangiomas typically do not show increased metabolic activity, which helps differentiate them from more aggressive or metabolically active lesions.