Kamstrup MR, Gniadecki R, Friberg L. Integrated Positron-Emission Tomography and Computed Tomography Manifestations of Cutaneous T-Cell Lymphoma. Arch Dermatol. 2012;148(12):1420-1422. doi:10.1001/archdermatol.2012.3198
Author Affiliations: Departments of Dermatology (Drs Kamstrup and Gniadecki) and Clinical Physiology and Nuclear Medicine (Dr Friberg), Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
Mycosis fungoides (MF) and Sézary syndrome (SS) represent the most common types of primary cutaneous T-cell lymphomas (CTCLs).1 Current guidelines recommend [18F]-fluorodeoxyglucose positron-emission tomography (FDG-PET) plus computed tomography (CT) scan for staging purposes in all patients except in cases of early-stage disease (IA-IB).1 However, the application of FDG-PET in CTCL has not been widely documented.2- 4 In this study, we retrospectively evaluated the findings of FDG-PET/CT scans in 41 patients with CTCL.
Patients with MF and SS who underwent FDG-PET/CT scans (Gemini TOF 64 slice PET/CT scanner; Philips Healthcare Inc) either at the time of diagnosis or at the time of suspected relapse or progression over a 4-year period at our cutaneous lymphoma clinic were retrospectively enrolled in this study. Twenty patients (stage IA-IB) did not undergo PET/CT scans because patients with limited disease were not scanned systematically. The clinical follow-up period was a minimum of 6 months. Disease was staged according to a well-recognized staging system.1
An experienced nuclear medicine physician reviewed all scans, and FDG avidity was assigned to lymphomatous involvement if it was in agreement with histologic, clinical, and/or radiographic data. Results were graded visually as equivocal and positive when FDG avidity above background level was slightly and markedly enhanced, respectively. Relative uptake value was defined as the ratio of the mean FDG signal from the metabolically active lesion with the highest FDG uptake to the mean background activity in the liver (tumor to liver ratio [T:L]). Lymphadenopathy was diagnosed when the longest transverse diameter of the lymph node was 1.5 cm or longer. Data are presented as median values with respective ranges. The Danish Bioethics Committee for the Capital Region waived the need for ethical approval.
Overall, PET findings were considered suggestive of malignancy in 14 of 44 total scans (32%): 1 of 12 in stage IA scans (8%); 1 of 12 in stage IB (8%); 5 of 7 in stage IIB (71%); 1 of 4 in stage IIIA (25%); and 6 of 9 in stage IVA (67%) (Table). While cutaneous lesions of patches, plaques, and erythroderma showed no abnormalities on PET/CT scans, tumors (T:L, 2.9 [range, 0.5-5.7]), were detected consistently. We found no evidence of differences in the T:L of tumors with different histologic subtypes.
Six patients with MF and 6 with SS (1 SS followed by transformed MF) had clinical lymphadenopathy, which in 8 patients showed FDG avidity. In patients with transformed cutaneous disease (2 stage IIB and 2 stage IVA), PET/CT scans demonstrated abnormal FDG uptake (T:L, 2.8 [range, 2.2-3.1]) and lymphadenopathy. Analysis of biopsy specimens confirmed transformed nodal histologic characteristics in 2 patients. At last follow-up, all had progressive disease or had died due to disease progression.
Seven patients with MF (1 stage IA, 3 IB, 3 IIIA), which included 1 with clinical adenopathy, had FDG uptake of equivocal clinical significance (T:L, 0.9 [range, 0.6-1.2]). By CT evaluation, 6 had lymphadenopathy. Biopsies were not performed, but all patients had stable disease with no signs of nodal involvement at last follow-up indicative of dermatopathic changes.2,5
Single enlarged nodes described in 2 stage IB cases were not confirmed by PET/CT. Of 6 SS cases with palpable lymphadenopathy, FDG avidity was observed in 4 (T:L, 1.4 [range, 1.1-1.8]) (tumor size, >15 mm), 1 had nodal biopsy specimens classified as dermatopathic lymphadenopathy; and 1 had nodal biopsy specimens classified as early involvement of lymphoma (T:L, 1.8). Two SS cases had absence of nodal FDG uptake and nodal sizes smaller than 15 mm on CT.
Visceral disease was found on PET/CT scans in 5 of the 44 cases (11%), but none was diagnosed as CTCL (Table). Focal FDG avidity resulted in the diagnosis of a diffuse large-cell lymphoma in the parotid gland, liver metastases from a cholangiocarcinoma, and a lung lesion (not investigated further owing to the advanced lymphoma stage) in patients with stage IB, IVA, and IIB disease, respectively. Lung cancer and a tubulovillous adenoma of the colon were detected incidentally in a patient with stage IIB disease and one with stage IIIA disease, respectively. After assessment of PET scans, and guided by these results, the lesions were also visible on CT except in the case of the colon adenoma, for which the CT finding was uncertain, but coloscopy confirmed the diagnosis.
Our results offer no evidence that PET/CT provides any information beyond that revealed by a physical examination in assessing cutaneous disease in MF and SS. In this, they concur with studies suggesting that hypermetabolic activity is rarely seen except in tumors.2- 4
Assessment of nodal involvement in CTCL is difficult because many patients have dermatopathic lymphadenopathy, and lymphomatous involvement can occur in normal-sized lymph nodes.1 The present study is limited by lack of nodal biopsy specimens, but a recent prospective study of 13 MF and SS cases demonstrated a correlation between high FDG accumulation and histologic grade of nodal involvement or large-cell transformation.5
We did not find evidence of visceral spread in our patient population but found a high rate of concomitant malignant neoplasms, which is not unusual in CTCL.1 Though the CT component also provided information, it suggests a role for imaging techniques in disclosing concurrent neoplasia, at least in advanced CTCL phases.
In conclusion, FDG-PET/CT did not detect additional lymphoma involvement with modification of clinical stage. However, in 11% of patients (5 of 44), PET/CT identified visceral lesions that required further clinical workup and/or treatment. Further studies are required to address clinical usefulness of PET/CT in CTCL.
Correspondence: Dr Kamstrup, Department of Dermatology, Bispebjerg Hospital, Bispebjerg Bakke 23, Copenhagen DK-2400, Denmark (firstname.lastname@example.org).
Accepted for Publication: June 25, 2012.
Author Contributions: All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Kamstrup, Gniadecki, and Friberg. Acquisition of data: Kamstrup and Friberg. Analysis and interpretation of data: Kamstrup, Gniadecki, and Friberg. Drafting of the manuscript: Kamstrup and Friberg. Critical revision of the manuscript for important intellectual content: Kamstrup, Gniadecki, and Friberg. Obtained funding: Gniadecki and Friberg. Administrative, technical, and material support: Kamstrup, Gniadecki, and Friberg. Study supervision: Gniadecki and Friberg.
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank Markus Lonsdale, PhD, MPE, for technical assistance with PET/CT scans.