Abstract:

Case: An 84-year-old woman presented for evaluation of an enlarging, painful, ulcerated tumor on the right shoulder. She reported progressive shoulder pain for several months preceding the rapid development of the tumor over a period of several weeks. She denied a history of skin cancer, other primary malignancies, immunosuppression, trauma, or other symptoms such as fevers, weight loss, or night sweats. Biopsy revealed a diffuse infiltrate of medium to large lymphocytes throughout the dermis with abundant mitoses and necrosis. The tumor cells were diffusely positive for CD20 and Ki-67 proliferative index staining highlighted 75% of the infiltrate. Fluorescence in situ hybridization demonstrated the presence of MYC and BCL-2 rearrangements, confirming the diagnosis of diffuse large B cell lymphoma (DLBCL). The patient was treated with a combination of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-miniCHOP), which decreased tumor size and reduced pain. Background: Histopathologically, DLBCL is characterized by lymphoma cells arranged in a diffuse pattern with possible sclerosis, geographic necrosis, single cell apoptosis, and high mitotic rate. A starry sky pattern is observed in 10% of cases and is associated with high proliferation. Immunohistochemistry typically reveals expression of CD19, CD20, and CD22 along with PAX5, BOB.1, and OCT2 in neoplastic cells. Extra-nodal disease in DLBCL is present in approximately 40% of cases, and the skin is the second most common site of involvement after the gastrointestinal tract. A diagnosis of primary cutaneous B cell lymphoma can be established if there is a lack of systemic and nodal involvement.

Financial Disclosure:
No current or relevant financial relationships exist.

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Siddharth Srikakolapu, BA