Werner Kempf

• MD
• Consultant at University of Zurich

Background Primary cutaneous anaplastic large cell lymphoma (pcALCL) and lymphomatoid papulosis (LyP) are indolent CD30‐positive lymphoproliferative disorders that rarely express TCR‐γδ. However, primary cutaneous gamma‐delta T‐cell lymphoma (pcGDTCL), characterized by TCR‐γδ expression on neoplastic cells, is a rare, aggressive cutaneous T‐cell ly...

Based on histologic and genetic patterns, the current World Health Organization (WHO) classification distinguishes six subtypes of lymphomatoid papulosis (Lyp). The aim of our article was to analyze the frequency of histologic and immunohistochemical features of different Lyp subtypes reported in the literature. We used PubMed advanced search build...

Zusammenfassung Hintergrund Die Inzidenz der kutanen Leishmaniose (CL) in der Schweiz nimmt aufgrund von Migration und Globalisierung zu. Ziel dieser Arbeit war es, die Inzidenz der CL in der Schweiz zu untersuchen und die klinischen und histopathologischen Schwierigkeiten bei der Diagnose der CL zu identifizieren. Patienten und Methodik In diese...

Background Cutaneous leishmaniasis (CL) incidence in Switzerland is rising due to factors like migration and globalization. The aim of this work was to investigate CL frequency in Switzerland and identify clinical and histopathological difficulties in diagnosing CL in a non‐endemic country. Patients and Methods This retrospective study evaluated t...

Zusammenfassung Die kürzlich veröffentlichte fünfte Ausgabe der „World Health Organization classification of hematolymphoid tumors: lymphoid neoplasms“ bietet eine Umstrukturierung der Hierarchie der Entitäten. Im Allgemeinen wurden neue (definitive) Entitäten sowie tumorähnliche Läsionen aufgenommen. Die primären kutanen B‐Zell‐Lymphome (CBCL) wur...

Background The subcellular distribution of CD30 on mast cells and the presence of eosinophils in cutaneous mastocytosis require further investigation, especially as the cell surface expression of CD30 is critical for the therapeutic response of systemic mastocytosis to brentuximab vedotin. Objective Investigation of 147 biopsy specimens from 143 p...

The recently published 5 th edition of the “World Health Organization classification of hematolymphoid tumors: lymphoid neoplasms” provides a hierarchical reorganization. In general, new (definitive) entities as well as tumor‐like lesions were included. Primary cutaneous B‐cell lymphomas (CBCL) received a thorough review. A new class/family of cuta...

Background: Primary cutaneous lymphomas are a distinct group of rare lymphoid neoplasms with absence of extracutaneous lymphomas at the time of presentation. They are rare in Nepal and no data on cutaneous lymphoma have been published from this country till date.Methods: This retrospective study included 15 cases of cutaneous lymphomas retrieved fr...

Background Lymphomatoid Papulosis (LyP) is a rare cutaneous T-cell lymphoproliferative disorder. Comprehensive data on LyP in the paediatric population is scarce. Objectives To characterize epidemiological, clinical, histopathological, and prognostic features of paediatric LyP. Methods This was a retrospective, multicentre international cohort st...

The classification of primary cutaneous lymphomas and lymphoproliferative disorders (LPD) is continuously evolving by integrating novel clinical, pathological and molecular data. Recently two new classifications for haematological malignancies including entities of cutaneous lymphomas were proposed: the 5th edition of the WHO classification of haem...

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (γδ) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous γδ T-cell lymphoma (PCGDTL) or γδ mycosis fungoides. We performed a clinicopathologic analysis of the larg...

(1) Background: Various cutaneous adverse drug reactions (ADRs) are observed with the implementation of mRNA COVID-19 vaccines. To gain insight into the clinicopathologic features, we analyzed the correlation of histological and clinical data in 48 patients with these ADRs. (2) Methods: Single-center retrospective study in patients with ADRs after...

(1) Background: Various cutaneous adverse drug reactions (ADRs) are observed with the development of mRNA COVID-19 vaccines. To gain insight into the clinicopathologic features, we analyzed the correlation of histological and clinical data in 48 patients with these ADRs.; (2) Methods: Single-center retrospective study in patients with ADRs post-mRN...

Panniculitis, characterized by inflammation of the subcutaneous adipose tissue, displays diverse clinical and dermatohistopathological phenotypes. However, the underlying pathomechanisms remain largely unknown, with limited studies pointing to a delayed-type III/IV hypersensitivity reaction. In the present study, we aimed to gain new insights into...

Background: Primary cutaneous gamma-delta T-cell lymphoma (PC-GDTCL} is a rare, aggressive form of cutaneous T-cell lymphoma first acknowledged by the World Health Organization in 2008. The prognosis is poor, and differentiation of PC-GDTCL from overlapping entities is crucial, as their behavior and treatment vary. One of the key diagnostic immunop...

Leukemia cutis corresponds to skin infiltration by malignant hematopoietic cells. It is most commonly reported in acute myeloid leukemia, particularly in subtypes with a monocytic component. Its clinical manifestations are extremely variable, and histopathologic diagnosis of cutaneous leukemic infiltrates may be challenging. We report the first cas...

Purpose: Dedifferentiated melanoma (DedM) poses significant diagnostic challenges. We aimed to investigate the clinical, histopathological and molecular features of DedM. Methylation signature (MS) and copy number profiling (CNP) were carried out in a subgroup of cases. Patients and methods: A retrospective series of 78 DedM tissue samples from...

Background: Mycosis fungoides is the most common subtype of cutaneous T-cell lymphoma, in which the expression of cluster of differentiation 30 (CD30)+ subtype can now be treated with the CD30 antibody conjugate brentuximab vedotin. Diagnostic methods are based on immunohistochemical (IHC) staining followed by manual assessment by pathologists, wh...

Linked Article: Wang et al. Br J Dermatol 2022; 187:970–980.

Endemic Burkitt lymphoma (eBL) is an aggressive B cell cancer characterized by an IgH/c-myc translocation and the harboring of Epstein–Barr virus (EBV). Evidence accumulates that CD4 + T cells might contribute to eBL pathogenesis. Here, we investigate the presence of CD4 + T cells in primary eBL tissue and their potential dichotomous impact on an E...

We herein present an overview of the upcoming 5th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the re...

Background The proportion of Merkel cell carcinomas (MCCs) in solid‐organ transplant recipients (SOTR) harbouring Merkel cell polyomavirus (MCPyV) is unknown, as are factors affecting their outcomes. Objective To describe clinicopathological features of MCC in SOTR, investigate the tumoral MCPyV‐status and identify factors associated with tumour o...

Aims: Evaluation of the frequency, subcellular localization, and variability of CD30 expression in mycosis fungoides. Methods: This retrospective multicenter study investigated 135 biopsy specimens of 95 patients with mycosis fungoides for CD30 expression and CD30 staining pattern in relation to histomorphologic criteria, eosinophils and tumor s...

Malignant lymphomas of the skin form a heterogeneous group of neoplastic diseases with a broad spectrum of clinical, histological, and phenotypic manifestations, with cutaneous T-cell lymphomas and in particular mycosis fungoides being the most common lymphoma form. Frequency, prognosis and thus also the treatment of cutaneous lymphomas differ sign...

We report the largest series so far of granulomatous pigmented purpuric dermatosis (GPPD), a rare variant of pigmented purpuric dermatoses (PPD). GPPD can cause diagnostic difficulties as it can be mistaken clinically and histopathologically with numerous inflammatory and infectious dermatoses or even cutaneous T‐cell lymphoma. We compared the hist...

Kutane T-Zell-Lymphome (CTCL) machen den Großteil aller primären kutanen Lymphome (CL) aus. 80 % aller Fälle von CTCL wiederum entfallen auf Mycosis fungoides (MF) und CD30-positive lymphoproliferative Erkrankungen der Haut. Das klinische Bild der verschiedenen Formen von CTCL zeigt Überschneidungen. Darum ist die klinisch-pathologische Korrelation...

Background The differential diagnosis of atypical dermal non-epidermotropic CD8+lymphocytic infiltrates includes a heterogenous spectrum of lymphoproliferations with overlapping histological and phenotypic features, but divergent clinical manifestations and prognoses. As these neoplasms are rare, more data on their clinicopathological presentation...

This updated second edition provides a structured and highly illustrated guide to dermatopathology. It focuses on the most common dermatopathological diagnoses and presents their clinical, histological, and differential diagnostic features of the diseases. New chapters cover various inflammatory diseases such as interstitial granulomatous dermatiti...

Most common cutaneous T-cell lymphoma with characteristic clinical and histological features.

Benign vascular proliferation consisting primarily of capillaries.

Autoimmune bullous dermatosis with acantholysis mediated by antibodies directed against desmoglein 1. Some cases are drug-induced

Inflammation of hair follicle and adjacent connective tissue, caused by variety of infections, as well as by irritants.

Benign proliferation of enlarged sebaceous glands.

Reactive disorder on the ear helix with both epidermal damage and degenerative changes in dermis and underlying cartilage.

Localized small superficial ulcer with fibrinous-hemorrhagic exudate, neutrophils and sometimes bacteria. Subepidermal fibrin deposits with sparse or modest mixed perivascular infiltrates.

Spread of systemic malignancy to skin via blood or lymphatics. Most common sources are breast, colon and bronchial carcinomas, as well as metastatic melanoma.

Immunologic-allergic reaction usually triggered by herpes simplex virus or medications. When medications are involved, progression to more severe skin reactions such as Stevens-Johnson syndrome possible

Urticaria is a disease featuring multiple, usually pruritic, hives triggered by IgE-mediated immediate allergic reactions, as well as a variety of other triggers (mast cell degranulating agents, dietary histamines, physical triggers)

Neoplastic proliferation of Langerhans cells in the skin and other organs.

Area of permanent aberrant cutaneous differentiation caused by genetic mosaicism, usually following lines of Blaschko.

The tissues are embedded in paraffin, cut into 3–6 micron sections, placed on glass microscopic slides and stained. The standard stain in dermatopathology is hematoxylin and eosin (H & E stain) which stains the nuclei blue and the cytoplasm pink.

There are several ways of obtaining a skin biopsy; each has advantages and disadvantages.

Epithelial cyst with epidermal type of keratinization, arising either from infundibular follicular epithelium or through post-traumatic deposit of epidermal fragments in dermis.

When starting, the simplest approach is to examine the epidermis, then the dermis and finally the subcutaneous fat. This approach reduces the likelihood of overlooking something. For this reason, we have arranged this book, starting with epidermal changes and moving down through dermal and subcutaneous lesions.

Common genodermatosis inherited in an autosomal dominant fashion

Focal increase in melanin in basal layer epithelial cells secondary to increased melanin production and transfer, but without significant increase in number of melanocytes.

Tick-borne infection caused by borrelial spirochetes (B. burgdorferi, B. afzelii, B. garinii) with both cutaneous and systemic manifestations; also known as Lyme disease.

Cutaneous manifestations of intolerance reactions to medications; mechanism may be toxic or immunologic; wide spectrum of clinical and histological variants

Most common inflammatory panniculitis. Most cases idiopathic; common triggers include drugs, pregnancy, underlying infections (often gastrointestinal) and sarcoidosis

Post-traumatic or idiopathic collection of mucin in the dermis, usually on digits; not a true cyst but pseudocyst.

Inflammatory dermatosis of unknown etiology. Multiple lesions perhaps associated with diabetes mellitus

Destruction of small post-capillary venules by immunologic reaction often triggered by infectious agents or drugs

Allergic or toxic-irritant reaction with various clinical and histological stages and patterns; eczema is a synonym

Thickening of the spinous layer. One can distinguish between broad-based acanthosis as in chronic dermatitis and psoriasis-form acanthosis with elongated rete ridges as in psoriasis.

Background Histopathological classification of basal cell carcinoma (BCC) has important prognostic and therapeutic implications, but reproducibility of BCC subtyping among dermatopathologists is poor. Objectives To obtain a consensus paper on BCC classification and subtype definitions. Methods A panel of 12 recognized dermatopathologists (G12) fr...

Objective Cutaneous T-cell lymphoma (CTCL) is a malignant manifestation in the skin. The most popular subtype is mycosis fungoides (MF). The straight focus on the molecular background of the malignancy in the last decades lead into new therapeutic possibilities. The subtype CD30+ MF can be nowadays treated with the CD30 antibody conjugate brentuxim...

The correct interpretation of biomarkers, such as CD30, is critical and influences therapeutic decision. This retrospective multicenter study investigated 135 biopsy specimens of 95 patients with mycosis fungoides digitally for CD30 expression and CD30 staining pattern, histomorphologic criteria and presence of eosinophils in relation to tumor stag...

Cutaneous pseudolymphomas (C-PSL) represent an excessive immune response, which mimics clinically and/or histologically a malignant lymphoma. The clinical, histological, and phenotypic spectrum in C-PSL depends upon the causative agent and the individual immunologic response of the host. The clinical presentation of C-PSL encompasses solitary, loca...

Importance: Reactions to tattoo may simulate common dermatosis or skin neoplasms. Histopathology allows diagnosis and helps determining the level and degree of inflammation associated, consequently orientating treatment. Objective: To describe the histological features found in biopsies of cutaneous reactions to tattoo. Design: This study was...

To prevent SARS‐CoV2 infection, mRNA vaccines have been developed including the mRNA‐1273 (Moderna), a lipid‐nanoparticle–encapsulated mRNA vaccine (1). In some individuals a cutaneous localized reaction with erythema and swelling on the upper arm at the injection site occurs which is referred as “COVID arm” (2, 3). It is considered as delayed type...

Introduction: Primary cutaneous marginal zone B-cell lymphoma (MZL) follows an indolent clinical course. Histopathologically, there is a polymorphous infiltrate that includes small lymphocyte-like and centrocyte-like B cells and plasma cells usually with a substantial T-cell fraction. Primary cutaneous CD4+ small/medium T-cell lymphoproliferative...

Aims Cutaneous involvement by classic Hodgkin lymphoma (CHL) is an extraordinarily rare phenomenon in the current era. To date, no single large case series of cutaneous involvement by Hodgkin lymphoma has ever been reported in the literature. Methods and results A total of 25 cases of classic Hodgkin lymphoma were found. All cases represented exam...

Primary extramedullary plasmacytoma is rare monoclonal proliferation of plasma cells, which arise in various nonosseous anatomic locations without detectable underlying systemic disease. Historically, cutaneous infiltrates rich in mature neoplastic plasma cells have fallen into one of the following categories, plasmacytoma, lymphoplasmacytic lympho...

Cutaneous T‐cell lymphomas (CTCL) represent the majority of primary cutaneous lymphomas (CL). Mycosis fungoides (MF) and cutaneous CD30+ lymphoproliferative disorders account for 80% of all CTCL. CTCL show overlapping histological features. Thus clinical‐pathological correlation is of importance to achieve final diagnosis. MF shows a characteristic...

Lichen sclerosus et atrophicus (LSA) is a chronic inflammatory dermatosis of unknown etiology involving the genital and/or extragenital area, showing histopathologically a characteristic homogeneization and sclerosis of the superficial collagen with variably dense lymphoid infiltrates. Intraepidermal lymphocytes may be observed, and in some cases m...

Belousova and Kempf present a case of co-existence of hypopigmented mycosis fungoides and lymphomatoid papulosis.

Acral CD8(+) lymphoma is a provisional entity in the latest edition of the WHO Lymphoma Classification and is associated with a highly specific dot-like pattern of immunohistochemical expression of CD68. We report a case of an ulcerated solitary cutaneous lesion arising on the forehead of an adult man, which had a CD8(+) cytotoxic phenotype and are...

CD30, also known as tumor necrosis factor receptor 8 (TNF‐R 8), was primarily called Ki‐1 and is a cell surface molecule which has first been described from a group of pathologists from Kiel in 1982.¹ CD30 can be targeted with the drug brentuximab‐vedotin (BV), which is approved for relapsed or refractory CD30+ cutaneous T‐cell lymphoma (CTCL) incl...

Lichen aureus is a variant of pigmented purpuric dermatoses. The usual histology of lichen aureus is characterized by a subepidermal dense, band‐like lymphocytic infiltrate, extravasated erythrocytes and hemosiderin deposits. We report three patients with lichen aureus on the extremities with similar clinical, dermoscopic and histopathological find...

This chapter describes the clinical features (CFs) and histological features (HFs) of a few parasitoses with short concise text and information in bullet point style. The discussion is accompanied by several high‐resolution pictures which illustrate the common patterns and variants of tumorous lesions of the skin and are helpfully contextualized by...

This chapter describes the clinical features (CFs) and histological features (HFs) of a few complications of sepsis with short concise text and information in bullet point style. The discussion is accompanied by several high‐resolution pictures which illustrate the common patterns and variants of tumorous lesions of the skin and are helpfully conte...

Helminths are macroparasites, usually affecting the intestinal tract, the lymph, or blood vessels, and occasionally the skin. This chapter describes the clinical features (CFs) and histological features (HFs) of a few helminthic infections with short concise text and information in bullet point style. The discussion is accompanied by several high‐r...

This chapter describes the clinical features (CFs) and histological features (HFs) of a few bacterial infections with short concise text and information in bullet point style. The discussion is accompanied by several high‐resolution pictures which illustrate the common patterns and variants of tumorous lesions of the skin and are helpfully contextu...

This chapter describes the clinical features (CFs) and histological features (HFs) of a few fungal infections with short concise text and information in bullet point style. The discussion is accompanied by several high‐resolution pictures which illustrate the common patterns and variants of tumorous lesions of the skin and are helpfully contextuali...

This chapter describes the clinical features (CFs) and histological features (HFs) of a few viral infections with short concise text and information in bullet point style. The discussion is accompanied by several high‐resolution pictures which illustrate the common patterns and variants of tumorous lesions of the skin and are helpfully contextualiz...