Granulomatous dermatitis: a rare pitfall in lymphoma staging with [18F]FDG-PET/CT

A 36-year-old male with anaplastic large T cell lymphoma (A; nodal manifestations in the left iliac and left inguinal region, arrow) who had received six cycles of chemotherapy (brentuximab vedotin, cyclophosphamide, doxorubicin, and prednisone) presented for restaging prior to autologous stem cell transplantation. A few days earlier, the patient had noticed multiple new tender subcutaneous nodules, and erythemato-squamous, polymorphous, partially atrophic plaques all over his body (B1). [18F]FDG-positron emission tomography/computed tomography (PET/CT) showed complete metabolic response of primary lymphoma manifestations but revealed intense tracer accumulation in the disseminated subcutaneous nodules (B, axial image B2). Besides cutaneous involvement by T cell lymphoma, differential diagnoses included cutaneous sarcoidosis and pityriasis rosea. Biopsy of a subcutaneous nodule revealed no evidence of malignancy but granulomatous inflammation (B3) most consistent with reactive granulomatous dermatitis. After initiation of prednisone therapy, all (sub-)cutaneous lesions quickly resolved, and the patient was eligible for stem cell transplantation. Follow-up [18F]FDG-PET/CT demonstrated only residual tracer uptake of some lesions and a sustained complete lymphoma response (C). Reactive granulomatous dermatitis is a very rare skin disease with only several hundred cases reported worldwide so far [1], most commonly associated with autoimmune disorders such as rheumatoid arthritis. Furthermore, it has been associated with hematologic malignancies, including — in approximately 3% of cases — (B cell) lymphoma [1,2,3]. To our knowledge, this is one of the very first cases of granulomatous dermatitis in anaplastic large T cell lymphoma [4], and the first visualization of granulomatous dermatitis by [18F]FDG-PET/CT mimicking cutaneous lymphoma manifestations

Reduced splenic uptake on 68Ga-Pentixafor-PET/CT imaging in multiple myeloma - a potential imaging biomarker for disease prognosis

Beyond being a key factor for tumor growth and metastasis in human cancer, C-X-C motif chemokine receptor 4 (CXCR4) is also highly expressed by a number of immune cells, allowing for non-invasive read-out of inflammatory activity. With two recent studies reporting on prognostic implications of the spleen signal in diffusion-weighted magnetic resonance imaging in patients with plasma cell dyscrasias, the aim of this study was to correlate splenic (68)Ga-Pentixafor uptake in multiple myeloma (MM) with clinical parameters and to evaluate its prognostic impact. METHODS: Eighty-seven MM patients underwent molecular imaging with (68)Ga-Pentixafor-PET/CT. Splenic CXCR4 expression was semi-quantitatively assessed by peak standardized uptake values (SUV(peak)) and corresponding spleen-to-bloodpool ratios (TBR) and correlated with clinical and prognostic features as well as survival parameters. RESULTS: (68)Ga-Pentixafor-PET/CT was visually positive in all MM patients with markedly heterogeneous tracer uptake in the spleen. CXCR4 expression determined by (68)Ga-Pentixafor-PET/CT corresponded with advanced disease and was inversely associated with the number of previous treatment lines as compared to controls or untreated smouldering multiple myeloma patients (SUV(peak)Spleen 4.06 ± 1.43 vs. 6.02 ± 1.16 vs. 7.33 ± 1.40; (P5.79 ((P<) 0.001). Multivariate Cox analysis confirmed SUV(peak)Spleen as an independent predictor of survival (HR 0.75;P= 0.009). CONCLUSION: These data suggest that splenic (68)Ga-Pentixafor uptake might provide prognostic information in pre-treated MM patients similar to what was reported for diffusion-weighted magnetic resonance imaging. Further research to elucidate the underlying biologic implications is warranted

Biodistribution and radiation dosimetry of [99mTc]Tc-N4-BTG in patients with biochemical recurrence of prostate cancer

Abstract Background In patients with prostate cancer (PCa), imaging with gastrin-releasing peptide receptor (GRPR) ligands is an alternative to PSMA-targeted tracers, particularly if PSMA expression is low or absent. [99mTc]Tc-N4-BTG is a newly developed GRPR-directed probe for conventional scintigraphy and single photon emission computed tomography (SPECT) imaging. The current study aims to investigate the safety, biodistribution and dosimetry of [99mTc]Tc-N4-BTG in patients with biochemical recurrence (BCR) of PCa. Results No adverse pharmacologic effects were observed. Injection of [99mTc]Tc-N4-BTG resulted in an effective dose of 0.0027 ± 0.0002 mSv/MBq. The urinary bladder was the critical organ with the highest mean absorbed dose of 0.028 ± 0.001 mGy/MBq, followed by the pancreas with 0.0043 ± 0.0015 mGy/MBq, osteogenic cells with 0.0039 ± 0.0005 mGy/MBq, the kidneys with 0.0034 ± 0.0003 mGy/MBq, and the liver with 0.0019 ± 0.0004 mGy/MBq, respectively. No focal tracer uptake suggestive of PCa recurrence could be revealed for any of the patients. Conclusion [99mTc]Tc-N4-BTG appears to be a safe diagnostic agent. Compared to GRPR-targeted PET tracers, this 99mTc-labelled SPECT agent could contribute to a broader application and better availability of this novel approach. Further research to assess its clinical value is warranted

Investigation of spleen CXCR4 expression by [68Ga]Pentixafor PET in a cohort of 145 solid cancer patients

Additional file 1. Supplemental Figures 1–7, which provide additional Kaplan-Meier survival curves and correlations of laboratory parameters as mentioned in the results section

PROLONGED AND INTENSE UPTAKE OF [177LU]LU-FAP-RTX IN MYOEPITHELIAL CARCINOMA: A CASE REPORT

Introduction/Justification: We present a case of a 71-year-old male patient diagnosed with myoepithelial carcinoma of the pelvis and perineum, who underwent fibroblast activation protein (FAP)-directed radioligand therapy and presented long lasting tumor retention as detected by late whole-body scans. Report: The patient had been previously submitted to neoadjuvant radiation therapy and surgery, with tumoral relapse at the surgical margins in the gluteal region. Lesions displayed a slow and progressive sarcomatoid growth pattern, with sacral osteolytic involvement, accompanied with obturatory and left common iliac lymph node metastases. Immunotherapy was initiated but discontinued due to grade IV diarrhea. With progressive disease evident on FDG PET/CT and no other viable chemotherapy indicated, FAPI radioligand therapy was proposed, given significant tracer uptake observed in FAP-directed PET/CT. The patient received an intravenous injection of 200 mCi of [177Lu]Lu-FAP-RTX, which was well tolerated, with no acute side effects reported. Blood tests remained within normal range. Beyond partial hair loss,no other adverse events were observed. Imaging studies including whole-body planar and SPECT/CT scans revealed intense tracer retention in the sacral mass and mild to moderate retention in the lymph node metastases up to 15 days post-treatment. Notably, indicative of a response to FAP-directed radioligand therapy, there was a resolution of drainage from a fistula in the intergluteal region. Follow-up imaging is still pending at the moment. Conclusion: This case is the first report on favorably sustained tumor retention of the radiopharmaceutical in a carcinoma patient undergoing FAP-directed radioligand therapy. With tumor response assessment still pending, longer follow-up and detailed observation is still necessary for a better understanding of potential benefits and side effects of FAP-directed radioligand therapy, especially in patients undergoing subsequent treatment cycles