Primary Cutaneous Aggressive Epidermotropic T-cell Research Articles

Genetics Abnormalities with Clinical Impact in Primary Cutaneous Lymphomas.

Simple SummaryThe genetic landscape of cutaneous T-cell lymphomas analyzed by sequencing high throughput techniques shows a heterogeneous somatic mutational profile and genomic copy number variations in the TCR signaling effectors, the NF-κB elements, DNA damage/repair elements, JAK/STAT pathway elements and epigenetic modifiers. A mutational and genomic stratification of these patients provides new opportunities for the development or repurposing of (personalized) therapeutic strategies. The genetic heterogeneity in cutaneous B-cell lymphoma parallels with the specific subtype. Damaging mutations in primary cutaneous diffuse large B-cell lymphoma of the leg type, involving MYD88 gene, or BCL6 and MYC translocations or CDKN2A deletions are useful for diagnostic purposes. The more indolent forms, as the primary cutaneous lymphoma of follicle center cell (somatic mutations in TNFRSF14 and 1p36 deletions) and the cutaneous lymphoproliferative disorder of the marginal zone cells (FAS gene), present with a more restricted pattern of genetic alterations.Primary cutaneous lymphomas comprise a heterogeneous group of extranodal non-Hodgkin lymphomas (NHL) that arise from skin resident lymphoid cells and are manifested by specific lymphomatous cutaneous lesions with no evidence of extracutaneous disease at the time of diagnosis. They may originate from mature T-lymphocytes (70% of all cases), mature B-lymphocytes (25–30%) or, rarely, NK cells. Cutaneous T-cell lymphomas (CTCL) comprise a heterogeneous group of T-cell malignancies including Mycosis Fungoides (MF) the most frequent subtype, accounting for approximately half of CTCL, and Sézary syndrome (SS), which is an erythrodermic and leukemic subtype characterized by significant blood involvement. The mutational landscape of MF and SS by NGS include recurrent genomic alterations in the TCR signaling effectors (i.e., PLCG1), the NF-κB elements (i.e., CARD11), DNA damage/repair elements (TP53 or ATM), JAK/STAT pathway elements or epigenetic modifiers (DNMT3). Genomic copy number variations appeared to be more prevalent than somatic mutations. Other CTCL subtypes such as primary cutaneous anaplastic large cell lymphoma also harbor genetic alterations of the JAK/STAT pathway in up to 50% of cases. Recently, primary cutaneous aggressive epidermotropic T-cell lymphoma, a rare fatal subtype, was found to contain a specific profile of JAK2 rearrangements. Other aggressive cytotoxic CTCL (primary cutaneous γδ T-cell lymphomas) also show genetic alterations in the JAK/STAT pathway in a large proportion of patients. Thus, CTCL patients have a heterogeneous genetic/transcriptional and epigenetic background, and there is no uniform treatment for these patients. In this scenario, a pathway-based personalized management is required. Cutaneous B-cell lymphoma (CBCL) subtypes present a variable genetic profile. The genetic heterogeneity parallels the multiple types of specialized B-cells and their specific tissue distribution. Particularly, many recurrent hotspot and damaging mutations in primary cutaneous diffuse large B-cell lymphoma of the leg type, involving MYD88 gene, or BCL6 and MYC translocations and BLIMP1 or CDKN2A deletions are useful for diagnostic and prognostic purposes for this aggressive subtype from other indolent CBCL forms.

High incidence of adnexotropism in cytotoxic cutaneous lymphomas

Primary cutaneous gamma-delta T-cell lymphoma (PCγδTCL) and primary cutaneous aggressive epidermotropic T-cell lymphomas (PCAETCL) are rare aggressive cytotoxic cutaneous lymphomas (CyCL) often difficult to diagnose. Histopathologically, PCAETCL and PCγδTCL may resemble mycosis fungoides (MF) and the presence of adnexotropism in CyCL (CyCL) contributes to this diagnostic challenge, especially in the setting of atypical and double-negative phenotypes. In this retrospective study clinical data and histopathological section of 91 patients were analyzed for signs of clinical and histopathological signs adnexotropism. Adnexotropism was identified in 48.4% (44/91) of cases, including PCAETCL (40.9%, 18/44), PCγδTCL and cytotoxic cutaneous lymphomas, not otherwise specified (CyCTCL, NOS) (43.2%, 19/44 and 15.9%, 7/44). Comparison between disease-related mortality with Kaplan-Meier survival analysis of non-adnexotropic vs adnexotropic CyCL did not show any significant difference between the two groups (P=0.8). Clinically they present with patches, plaques, and tumors and commonly with ulceration, but follicular prominence or alopecia are rare. Clinical signs of adnexotropism such as alopecia and hypo- or anhidrosis were rarely seen. Adnexotropism is a common finding in CyCL, especially in PCAETCL. Adnexotropic CyCL may be histopathologically difficult to distinguish from folliculotropic mycosis fungoides. A comprehensive IHC panel should be routinely performed in such cases.

Histopathological aspects and differential diagnosis of CD8 positive lymphomatoid papulosis

Lymphomatoid papulosis (LyP) belongs to CD30+ lymphoproliferative disorders with indolent clinical course. Classic histological subtypes, A, B and C are characterized by the CD4+ phenotype, while CD8+ variants, most commonly classified as type D, were reported in recent years. We present 14 cases of CD8+ LyP. In all patients, self-resolving or treatment-sensitive papules were observed. Of 14 cases 7 produced results with typical microscopic features of LyP type D mimicking primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma. The infiltration pattern in 4 of 14 cases were consistent with classic LyP type B, without CD30 expression in two cases, resembling mycosis fungoides (MF). The morphology of 2 of 14 cases shared a certain consistency with classic type A and C, lacking eosinophils and neutrophils. Extensive folliculotropism characteristic to type F was observed in 1 of 14 case. Significant MUM1 and PD1 expression were detected in 2 of 14 and 3 of 14 cases, respectively. We concluded that CD8+ LyP may present with different histopathological features compared with type D, similar to CD4+ LyP variants. Differential diagnoses include CD8+ papular MF, folliculotropic MF and anaplastic large cell lymphoma in addition to primary cutaneous aggressive epidermotropic T-cell lymphoma. We emphasise that rare CD8+ LyP cases may exist with CD30-negativity.