INTRODUCTION
Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma.1 Approximately 40% of cases have extranodal involvement that most commonly occurs in the gastrointestinal tract or head and neck (often presenting as Waldeyer's ring).1 Cases involving the skin and muscle are rare, and most commonly present as plaques, papules, small nodules, or ulcers.2 These lesions often have a red or bluish-red hue.2 Large exophytic masses are more common in other cutaneous malignancies such as basal cell carcinoma, and a much less common manifestation of DLBCL. We report a case of DLBCL presenting as a large exophytic mass that was successfully treated with chemotherapy alone.
CASE REPORT
A 48-year-old man presented with a mass on his left shoulder to the dermatology clinic. He had noticed a small lesion more than 10 years prior to presentation that started as a "pimple" that would wax and wane in size. It steadily enlarged before accelerating in growth 4 months before evaluation. A physical exam showed an exophytic, necrotic, ulcerated mass with foul-smelling necrotic drainage and enlarged lymph nodes in the left axillary basin (Figure 1). The clinical appearance was initially thought to be a cutaneous malignancy such as baso-squamous carcinoma, and urgent resection of the mass was planned.
However, a biopsy revealed a diffuse infiltrate of large, atypical B cells coursing through a fibrotic dermis (Figure 2A). The cells exhibited irregular nuclei, moderately dispersed chromatin, and distinct nucleoli (Figure 2B). The large B cells were positive for CD20 (Figure 2C), showed a germinal center-like/non-double-expressor (BCL2+/MYC-) immunophenotype, and exhibited a high proliferative index (Figure 2D). FISH showed no evidence of MYC rearrangement, leading to a diagnosis of diffuse large B
cell lymphoma, not otherwise specified (DLBCL, NOS). Positron emission tomography showed intensely FDG-avid left shoulder soft tissue mass as well as left axillary and left supraclavicular FDG-avid lymph nodes. He was then referred to Medical Oncology but was lost to follow-up.
