Aggressive Variant of Primary Cutaneous Anaplastic Large T-Cell Lymphoma: A New Role for 18F-FDG PET/CT

Systemic progression of primary cutaneous anaplastic large cell lymphoma in 18F-FDG PET/CT: a case report

Primary cutaneous anaplastic large cell lymphoma (pcALCL) is a type of skin T-cell lymphoma with a favorable prognosis. Some patients may experience recurrence, but systemic involvement is rare. Some studies suggest that systemic progression is associated with poor prognosis. The value of 18F-FDG PET/CT in diagnosing lymphoma has been recognized, but there is often controversy over the application value of 18F-FDG PET/CT in pcALCL. We present a rare case of pcALCL involving multiple systemic lesions, monitored and evaluated using 18F-FDG PET/CT to assist in clinical treatment decisions. Through this case, we consider that 18F-FDG PET/CT has significant value in diagnosing pcALCL. However, more clinical cases are needed to confirm whether high FDG uptake is associated with the invasiveness of pcALCL and the impact of high FDG uptake and Ki-67 expression on the progression and prognosis of pcALCL.

Composite Cutaneous Lymphoma (Iatrogenic Immunodeficiency-Associated Lymphoproliferative Disorder) in a Patient with Rheumatoid Arthritis Treated with Methotrexate: Staging and Evaluation of Response to Therapy with 18F-FDG PET/CT

A 67 year old woman with a 10 year history of rheumatoid arthritis (RA) treated with methotrexate and prednisone, presented with a 2 year history of worsening multiple cutaneous plaques of variable appearance. Two distinct skin lesions were biopsied to reveal a composite cutaneous lymphoma, possibly caused by long term methotrexate therapy. An [18F] fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was performed to stage the malignancy, and was later repeated to evaluate response to chemotherapy, which guided subsequent management. We present the PET/CT imaging findings of this very rare iatrogenic (methotrexate induced) immunodeficiency-associated lymphoproliferative disorder.

The utility of positron emission tomography with and without computed tomography in patients with nonmelanoma skin cancer

Combined positron emission tomography (PET) and computed tomography (CT) scans are widely used in the staging and monitoring of most malignancies. The differential for PET-positive cutaneous lesions includes primary skin cancers, infections, cutaneous metastases from distant malignancies, and benign neoplasms. In dermatology, PET/CT scans have been most widely studied in patients with melanoma and Merkel cell carcinoma. The role of PET/CT scans in the management of other cutaneous malignancies is less clear, but it has shown great promise in the management of patients with squamous cell carcinoma and cutaneous lymphoma. This review seeks to address the usefulness of PET/CT scans in nonmelanoma skin cancer and to provide guidance regarding the management of patients with incidental PET-positive nodules. Currently, there is limited experience with PET/CT scans for staging and monitoring of non-head and neck metastatic basal cell and squamous cell carcinomas, and results show limited sensitivity and specificity. We also address the evidence for management of an incidental PET-positive cutaneous nodule and recommend obtaining a biopsy specimen in patients with a known noncutaneous malignancy, a history of primary skin cancer, or a high risk of either cutaneous or noncutaneous malignancy.

Assessing Cutaneous Psoriasis Activity Using FDG-PET: Nonattenuation Corrected Versus Attenuation Corrected PET Images

Psoriasis is a chronic inflammatory skin condition characterized by well-circumscribed erythematous plaques with thick silvery scale. Infiltration of inflammatory cells such as lymphocytes, neutrophils, and macrophages and epidermal cell proliferation within psoriatic lesions may result in selective FDG accumulation. We present a 55-year-old patient with a 30-year history of psoriasis. Nonattenuation corrected PET/CT images demonstrated significant cutaneous FDG uptake corresponding to clinically apparent psoriatic lesions. However, in attenuation corrected (AC) FDG-PET images, the signal was substantially diminished and minimally detectable. Nonattenuation corrected FDG-PET images may be useful and preferable to AC images in assessing skin inflammation in psoriasis.