Bilateral Cutaneous Diffuse Large B-Cell Lymphoma on FDG PET/CT

F-18-FDG PET/CT findings of paraneoplastic dermatoses

Paraneoplastic dermatoses (PD) are defined as nonspecific skin disorders which are associated with internal neoplasms, but without direct association to primary tumors or metastases. Recognition of PD and the following surveillance may lead to the diagnosis of internal malignant neoplasms including early stage ones. Accurate imaging examinations in the following searching is essential in identifying the underlying neoplasms. Since whole-body 18-fluoro-2-deoxyglucose (F-18-FDG)-positron emission (PET)/computed tomography (CT) has been widely used in early diagnosis, staging of various malignant tumors, it may play a role for detection of underlying or occult malignant neoplasms in patients with PD. However, to date, only a few reports of FDG PET/CT findings of the associated neoplasms in PD patients have been cited in the literature. The present paper shows the cases of FDG-avid associated neoplasms in patients with PD in our 10-year experience in our institute, and reviews the well-known and/or relatively common PD and their associated neoplasms, and the previously reported cases of FDG-avid associated neoplasms in these patients.

Diffuse Cutaneous Angiosarcoma in the Scalp and Face Demonstrated on FDG PET/CT Imaging

ABSTRACT

Diffuse cutaneous angiosarcomas are rare. Herein, we reported FDG PET/CT findings of cutaneous angiosarcoma in a 59-year-old man. FDG PET/CT imaging was performed for staging, showing diffuse intense FDG uptake with an SUVmax of 19 in the scalp and face. Chemotherapy was recommended for this patient because surgery and radiotherapy were not appropriate due to the widespread skin involvement. Our case suggests that cutaneous angiosarcoma can present with diffuse skin involvement, and FDG PET/CT plays an important role in determining the treatment plan to avoid unnecessary surgery and radiotherapy.

Multimodality imaging and treatment strategy for malignant scalp neoplasms in adults

Malignant scalp masses deserve much attention as they have the potential to destroy local structures, recur and metastasize to distant organs. Moreover, malignant scalp lesions are known to be more aggressive in behavior than their counterparts elsewhere in the body. Multimodality imaging is essential in narrowing the differential diagnoses of scalp masses, as well as in differentiating benign from malignant masses. Furthermore, imaging is important in (1) evaluating the extent of tumor invasion in the scalp, (2) staging the disease, (3) guiding surgical biopsy and/or resection of the tumor, (4) preoperative planning and post-treatment surveillance of scalp tumors. An interdisciplinary treatment approach is crucial for the management of scalp malignancies given their complex and aggressive nature. This review seeks to describe the unique clinical and imaging characteristics of various types of malignant scalp masses, as well as to review their current treatment strategies.

Iatrogenic Cushing's syndrome on 18F-FDG-PET/CT: A pitfall in metabolic assessment of oncologic response

Iatrogenic Cushing's syndrome has very well-known stigmata on physical examination but can pose a diagnostic challenge when it rarely presents radiologically. We present a classic albeit rarely encountered imaging appearance of Iatrogenic Cushing's on ¹⁸F-FDG-PET/CT, with diffuse subcutaneous white adipose proliferation and metabolic activation in a 7-year old patient one-month after starting a high dose steroid regimen for lymphoma. There was an extreme shift in the expected FDG biodistribution with dominant localization to the subcutaneous adipose tissue. This metabolic shift led to sub-threshold visceral biodistribution, rendering the scan non-diagnostic with regards to assessment of oncologic response. Aside from detailing the characteristic imaging findings of Iatrogenic Cushing's and its clinical importance, we discuss the physiologic basis of this imaging pattern and the rarer differential diagnosis to consider when this pattern of uptake is encountered on ¹⁸F-FDG-PET/CT.

Subcutaneous mass concerning for sarcoma: a peculiar presentation of diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) can present in a number of different ways, including as a primary cutaneous lesion or at various other extranodal sites. However, it is rare for a DLBCL to present as a clinically subcutaneous mass without visible skin changes or nodal involvement. A 36-year-old man presented with a 4×4×1 cm subcutaneous mass to his shoulder with normal overlying skin which had been enlarging over 6 months. Physical exam and imaging together made a strong case for sarcoma, and the patient underwent a radical resection. The final pathological diagnosis returned as a diffuse B-cell lymphoma (germinal centre type). The patient subsequently healed and tolerated chemotherapy well. DLBCL can masquerade as a soft tissue mass at initial presentation. If the diagnosis is not clear, a biopsy should be pursued.

Zosteriform Secondary Cutaneous Diffuse Large B-Cell Lymphoma on FDG PET/CT

We present a case of a woman who had erythematous papules on the abdomen accompanied with numbness and local heat sensation. She had received chemotherapy for advanced follicular lymphoma. F-FDG PET/CT demonstrated band-like hypermetabolic lesions seemingly involving dermatomes of lower abdominal wall, which was confirmed as secondary cutaneous diffuse large B-cell lymphoma via skin biopsy.

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.

Diffuse Large B-Cell Lymphoma Infiltrating Limb Bones With a Few Lymphadenopathy Revealed on Whole-Body 18F-FDG PET/CT

A 74-year-old man presented to our hospital for a 2-month history of worsening feet and left hand swelling pain. Computed tomography reconstruction image and sagittal images of the left foot demonstrated multiple and irregular bone destruction. Orthopedic surgeon suspected tuberculosis or primary skeletal malignancy. ¹⁸F-FDG PET/CT revealed bone destruction and abnormal activity mainly in bones of both upper and lower extremities and a few lymphadenopathy at the region of left axilla and groin. Diagnosis of diffuse large B-cell lymphoma was eventually made. Subsequently, the patient was transferred to the department of oncology and responded well to antilymphoma therapy.