who-eortc classification for cutaneous lymphomas - Dermatology

SPTL is only used for cases with an α/β+ T-cell phenotype, whereas cases with a γ/δ+ T-cell phenotype
are included in the category of cutaneous γ/δ T-cell lymphomas. 32
Clinical features
SPTCL occur in adults as well as in young children, and both sexes are equally affected. Patients
generally present with solitary or multiple nodules and plaques, which mainly involve the legs, or may
be more generalized (Fig. 4A). Ulceration is uncommon. Systemic symptoms such as fever, fatigue and
weight loss may be present. The disease may be complicated by a hemophagocytic syndrome, which is
generally associated with a rapidly progressive course. 117 However, a hemophagocytic syndrome is
probably less common than in cutaneous γ/δ T-cell lymphomas with panniculitis-like lesions.
Dissemination to extracutaneous sites is rare. SPTL may be preceded for years or decades by an
15, 17, 117
seemingly benign panniculitis.
Histopathology
Histopathology reveals subcutaneous infiltrates simulating a panniculitis showing small, medium-sized or
sometimes large pleomorphic T cells with hyperchromatic nuclei and often many macrophages. The
overlying epidermis and dermis are typically uninvolved. 16, 116 Rimming of individual fat cells by
neoplastic T cells is a helpful, though not completely specific diagnostic feature. 32 (Fig. 4B). Necrosis,
karyorrhexis and cytophagocytosis are common findings. In the early stages the neoplastic infiltrates may
lack significant atypia and a heavy inflammatory infiltrate may predominate. 15,17,117
Immunophenotype
These lymphomas show a α/β+, CD3+, CD4-, CD8+ T-cell phenotype, with expression of cytotoxic
proteins. 14,16,17,32 (Fig. 4C). CD30 and CD56 are rarely, if ever, expressed.
Genetic features
The neoplastic T cells show clonal TCR gene rearrangements. Specific genetic abnormalities have not
been identified. EBV is absent.
Prognosis and predictive factors
In contrast to prior reports indicating that patients with a SPTL have a rapidly fatal course, recent studies
suggest that many patients with a SPTL (with a CD8+, α/β+ T-cell phenotype) have a protracted clinical
course with recurrent subcutaneous lesions but without extracutaneous dissemination or the development
of a hemophagocytic syndrome. 17,32 Based on the few published reports in which appropriate phenotyping
was performed, the 5-year-survival of such patients may be over 80% 32 , which is consistent with the data
presented in Table 2.
18