Abstract

Primary cutaneous follicle center lymphoma (PCFCL) is the most common primary cutaneous B-cell lymphoma (PCBCL). It is a low-grade lymphoma with an excellent prognosis. PCFCL with diffuse growth pattern and large cells are rare and histologically mimics primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), PCDLBCL, not otherwise specified, and systemic DLBCL. Though PCFCL has a 5-year survival rate of ? 95%, PCDLBCL-LT is typically more aggressive with a 40-50% 5-year survival rate. PCFCL follows a good prognosis regardless of growth pattern, the extent of disease, genetic profile, and cutaneous relapse. However, cutaneous relapse manifestation is seen in approximately 30% of patients after initial treatment. We present a case of a 72-year-old male who presented with a solitary erythematous 1.7 cm nodule on the right lateral eyebrow. The punch biopsy revealed an atypical dermal lymphoid infiltrate, arranged predominantly in a diffuse pattern with numerous mitotic figures and sparing the epidermis with a thin Grenz zone. The cells were predominantly large-sized with noncleaved, irregular nuclei and 1-¬3 prominent nucleoli. Immunohistochemical studies revealed a predominance of CD20-positive B-cells in the infiltrate. These cells were diffusely positive for BCL6 and CD10 and negative for BCL2, MUM1, TdT, EBER, and Cyclin D1. Ki67 demonstrated a high proliferation rate (>80%). CD23 highlighted the absence of germinal centers. CD30 stained only a few scattered cells. IGH gene rearrangement studies by PCR were positive for a clonal B-cell population. The tumor was completely excised with negative margins. The patient is doing well on follow-up with no recurrence.

Financial Disclosure:
No current or relevant financial relationships exist.