Katrin Kerl

Subcutaneous, blastic natural killer (NK), NK/T-cell, and other cytotoxic lymphomas of the skin: a morphologic, immunophenotypic, and molecular study of 50 patients.

A new group of subcutaneous, natural killer (NK), NK/T-cell, and other cytotoxic T-cell lymphomas of the skin has been recently described, and some have been included as distinct clinicopathologic entities in the classification of hematologic malignancies recently proposed by the World Health Organization. In the European Organization for Research and Treatment of Cancer classification for cutaneous lymphomas, they would be classified either as CD30- large T-cell lymphoma, small/medium pleomorphic T-cell lymphoma, or subcutaneous T-cell lymphoma. Precise clinicopathologic and prognostic features of all of them have not yet been well characterized. We studied retrospectively 81 biopsies from 50 patients with subcutaneous, blastic natural killer (NK), NK/T-cell, or other non–mycosis fungoides cytotoxic T-cell lymphomas of the skin. Clinical, morphologic, phenotypical, and genetic features and data on Epstein-Barr virus association allowed us to classify our cases according to the following 7 categories: a) subcutaneous “panniculitis-like” T-cell lymphoma (SPTCL): 10 cases (estimated 5-year survival: 80%); b) blastic NK-cell lymphoma: 12 cases (estimated 5-year survival: 0%); c) nasal-type extranodal NK/T-cell lymphoma: 5 patients (estimated 5-year survival: 0%); d) epidermotropic CD8+ T-cell lymphoma: 5 cases (estimated 5-year survival: 0%); e) cutaneous γ/δ T-cell lymphoma: 8 cases (estimated 5-year survival: 0%); f) cutaneous α/β pleomorphic T-cell lymphoma: 8 cases (estimated 5-year survival: 0%); and g) cutaneous medium/large pleomorphic T-cell lymphoma, not otherwise specified: 2 cases. Our study shows that these cutaneous lymphomas can be classified according to precise diagnostic categories. With the exception of SPTCL, analysis of follow-up data from our patients showed that these groups of lymphomas are characterized by an aggressive course, regardless of the diagnostic category.

The Nlrp3 inflammasome regulates acute graft-versus-host disease.

Conditioning therapies before transplantation induce the release of uric acid, which triggers the NLRP3 inflammasome and IL-1β production contributing to graft-versus-host disease.

IL-1β drives inflammatory responses to propionibacterium acnes in vitro and in vivo.

Acne vulgaris is potentially a severe skin disease associated with colonization of the pilo-sebaceous unit by the commensal bacterium Propionibacterium acnes and inflammation. P. acnes is considered to contribute to inflammation in acne, but the pathways involved are unclear. Here we reveal a mechanism that regulates inflammatory responses to P. acnes. We show that IL-1β mRNA and the active processed form of IL-1β are abundant in inflammatory acne lesions. Moreover, we identify P. acnes as a trigger of monocyte-macrophage NLRP3-inflammasome activation, IL-1β processing and secretion that is dependent on phagocytosis, lysosomal destabilization, reactive oxygen species, and cellular K+ efflux. In mice, inflammation induced by P. acnes is critically dependent on IL-1β and the NLRP3 inflammasome of myeloid cells. These findings show that the commensal P. acnes-by activating the inflammasome-can trigger an innate immune response in the skin, thus establishing the NLRP3-inflammasome and IL-1β as possible therapeutic targets in acne.

RASopathic Skin Eruptions during Vemurafenib Therapy

Purpose Vemurafenib is a potent inhibitor of V600 mutant BRAF with significant impact on progression-free and overall survival in advanced melanoma. Cutaneous side effects are frequent. This single-center observational study investigates clinical and histological features of these class-specific cutaneous adverse reactions. Patients and Methods Patients were all treated with Vemurafenib 960 mg b.i.d. within local ethic committees approved clinical trials. All skin reactions were collected and documented prospectively. Cutaneous reactions were classified by reaction pattern as phototoxic and inflammatory, hair and nail changes, keratinocytic proliferations and melanocytic disorders. Results Vemurafenib was well tolerated, only in two patients the dose had to be reduced to 720 mg due to arthralgia. 26/28 patients (93%) experienced cutaneous side effects. Observed side effects included UVA dependent photosensitivity (n = 16), maculopapular exanthema (n = 14), pruritus (n = 8), folliculitis (n = 5), burning feet (n = 3), hair thinning (mild alopecia) (n = 8), curly hair (n = 2) and nail changes (n = 2). Keratosis pilaris and acanthopapilloma were common skin reactions (n = 12/n = 13), as well as plantar hyperkeratosis (n = 4), keratoacanthoma (n = 5) and invasive squamous cell carcinoma (n = 4). One patient developed a second primary melanoma after more than 4 months of therapy (BRAF and RAS wild type). Conclusion Vemurafenib has a broad and peculiar cutaneous side effect profile involving epidermis and adnexa overlapping with the cutaneous manifestations of genetic diseases characterized by activating germ line mutations of RAS (RASopathy). They must be distinguished from allergic drug reaction. Regular skin examination and management by experienced dermatologists as well as continuous prophylactic photo protection including an UVA optimized sun screen is mandatory.

Resistance to FasL and tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in Sézary syndrome T-cells associated with impaired death receptor and FLICE-inhibitory protein expression

Because of the low proliferative potential of tumor cells in patients with Sézary syndrome (SzS), their accumulation has been suggested to be due to defective regulation of apoptosis. We analyzed the sensitivity to soluble Fas-ligand (FasL) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), 2 members of the TNF superfamily in peripheral blood leukocytes (PBL) from patients with SzS. Compared with healthy donors, CD4(+) cells from patients with SzS were completely resistant to FasL in 9 of 16 cases. Of these 9 FasL-resistant cases, 4 revealed a loss in Fas (CD95) expression, whereas the remaining 5 exhibited normal or enhanced Fas expression. In the latter 5 cases, the apoptosis inhibitor cFLIP was overexpressed in CD4(+)/CD26(-) tumor cells compared with CD4(+)/CD26(-) cells from Fas-expressing FasL-sensitive patients and healthy donors. Furthermore, resistance to TRAIL and tumor cell-restricted loss of TRAIL-receptor 2 were observed in 16 of 16 SzS PBLs. It is noteworthy that resistance to FasL could be overcome by the use of a hexameric FasL or upon exposure of SzS cells to interferon-alpha (IFN-alpha) or IFN-gamma, the latter by an increase of Fas expression. Our data on primary SzS lymphocytes reveal frequent resistance to apoptosis induced by FasL and TRAIL, which may contribute to their accumulation in patients with SzS and be relevant at a therapeutic level.

Primary cutaneous B-cell lymphomas

Cutaneous B‐cell lymphomas (CBCL) are the second most common form of primary cutaneous lymphomas. The cutaneous follicle center lymphoma and the cutaneous marginal zone lymphoma (extranodal MALT type lymphoma) account for the vast majority of CBCL and manifest with nodules. These two lymphoma entities have an indolent, slowly progressive course and an excellent prognosis despite a high rate of recurrences. In contrast, cutaneous diffuse large B‐cell lymphoma, leg type, and other rare forms of CBCL display an impaired prognosis and therefore require to be treated with multiagent chemotherapy and anti‐CD20 monoclonal antibodies in most cases. Clinico‐pathologic correlation, histology with immunohistochemical profile and genotyping as well as staging examinations are crucial diagnostic elements in the work‐up of CBCL.

Canakinumab in adults with steroid-refractory pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is a rare, neutrophilic, ulcerative skin disease that is difficult to treat, especially when unresponsive to steroids.

Cutaneous angiosarcoma: own experience over 13 years. Clinical features, disease course and immunohistochemical profile

Background  Cutaneous angiosarcoma (AS) is a rare malignant tumour of endothelial origin with very poor prognosis, frequent recurrences and high metastatic potential. Clinical suspicion is often raised too late, but histological findings and immunohistochemical assays have proved to be very helpful in the diagnostic process.

Prevalence of Merkel Cell Polyomavirus among Swiss Merkel Cell Carcinoma Patients

Background: Merkel cell carcinoma (MCC) is a malignant neuroendocrine neoplasm which shares structural and immunohistochemical features with neuroectodermally derived cells. One hypothesis claims that it arises from Merkel cells, highly innervated neuroendocrine cells involved in mechanoreception in the skin. The incidence rate of this cancer increases with age and sun exposure as well as after immunosuppression. Recently, the clonal integration of a newly identified polyomavirus called Merkel cell polyomavirus (MCPyV) was reported in up to 80% of MCC tissue. Here we report the incidence rate of MCPyV in MCC patients in Switzerland. Methods: We performed polymerase chain reaction in a collection of 32 samples obtained from pathology institutes around Switzerland. We used three different published primer sets. As control groups we used 7 squamous cell carcinoma samples and 11 normal skin samples. Conclusions: We detected viral DNA in 20 out of 30 cases of MCC and in 0 out of 19 control samples. The presence of viral DNA in 66.6% of our MCC tissue specimens confirms the high prevalence of MCPyV in MCC patients described in American, German, French and Hungarian patient collections.

Cutaneous lymphomas: an update. Part 1: T-cell and natural killer/t-cell lymphomas and related conditions

Abstract:Primary cutaneous T-cell lymphomas (CTCL) represent the majority of cutaneous lymphomas (CLs) and are a spectrum of diseases with a wide variety of clinical, histological, and phenotypic features and diverse biologic behavior. This review focuses on the observations on new variants of CTCL and recent developments in deciphering the pathogenetic mechanisms, which have implication for the nosologic concepts and future classification of CLs. Variants of mycosis fungoides (MF) such as the unilesional and the papular form have been characterized in more detail. Studies analyzed the expression of CD30 and PD-1 in MF and other forms of CTCL. New variants in the group of cutaneous CD30+ lymphoproliferative disorders include the epidermotropic CD8+ variant of lymphomatoid papulosis (type D) and angiocentric lymphomatoid papulosis (type E), which histologically mimic aggressive lymphomas, and therefore may be diagnostically challenging. Cutaneous proliferations of T cell–expressing markers of follicular helper T cells (PD-1, CXCL-13, and bcl-6) display a prognostically heterogeneous group. There is an increasing spectrum of CTCL with the expression of CD8 by tumor cells, including CD8+ MF, CD8+ forms of cutaneous CD30+ lymphoproliferative disorders, and CD8+ small/medium-sized lymphoproliferations, which are not included as distinct entities in the World Health Organization–European Organization for Research and Treatment of Cancer for CLs and the World Health Organization classification. Unusual presentations and incomplete phenotypes of blastic neoplasm of plasmacytoid dendritic cells are discussed. Clinicopathologic correlation is mandatory for the diagnosis of primary CLs. Analysis of genetic and epigenetic alterations in CLs revealed new diagnostic markers and putative targets for therapy of aggressive forms of CLs.