Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type: Diagnostic Considerations

Abstract

Context.—Primary cutaneous diffuse large B-cell lymphoma, leg type, may show features that overlap with other lymphomas. However, timely recognition of this entity can have important clinical and therapeutic implications. Objective.—To review the clinical, morphologic, and immunophenotypic characteristics of primary cutaneous diffuse large B-cell lymphoma, leg type, and juxtapose these features with other diagnostic considerations. In particular, other variants of primary cutaneous diffuse large B-cell lymphoma, as well as primary cutaneous follicle center lymphoma, will be reviewed. Additionally, systemic/extracutaneous lymphomas will be discussed, including diffuse large B-cell lymphoma, not otherwise specified, Epstein-Barr virus–positive diffuse large B-cell lymphoma of the elderly, and lymphomatoid granulomatosis. Data Sources.—Relevant literature will be reviewed and key differentiating findings will be highlighted. Conclusions.—Although primary cutaneous diffuse large B-cell lymphoma, leg type, may show aspects that overlap with other lymphomas, it can be distinguished from other entities in the differential diagnosis.

A literature revision in primary cutaneous B-cell lymphoma

“…[97077] Extracutaneous spreading is often reported, most commonly in lymph nodes, bone marrow, and nervous system. [78]…”

“…This immunophenotype is useful for the diagnosis of PCDLBCL, LT even if 10% of cases are negative for BCL-2 and MUM1/IRF4. [767882]…”

Case for diagnosis

“…The five-year survival is 50%. 3-5 Histological examination of tumor lesions shows a diffuse, monotonous cellular infiltrate of immunoblasts, without epidermotropism. The presence of the normal collagen band in the superficial dermis, separating the epidermis from the dermal lymphocytic infiltrate (Grenz zone) is a common finding in cutaneous B-cell lymphomas.…”

The diversity of diffuse large B-cell lymphoma in extranodal sites: overview and update

“…It accounts for a minority of primary cutaneous B-cell lymphomas. The most common site of involvement is the lower leg, although other cutaneous sites may be affected [23][24][25]. It usually presents as solitary, occasionally multiple, erythematous or violaceous nodules on one or both legs, often with ulceration.…”

“…These include heterozygous deletion of TNFAIP3 (A20), and mutations of CD79B, CARD11, and MYD88 resulting in amino acid substitutions, with more than one abnormality affecting a subset of cases [27]. The differential diagnosis of primary cutaneous DLBCL includes primary cutaneous follicle center lymphoma [25]. Cutaneous follicle center lymphoma is a proliferation of large and small centrocytes and centroblasts.…”