Arjen Nikkels

Comparative immunohistochemical study of herpes-simplex and varicella-zoster infections

Herpes simplex (HSV) and varicella-zoster (VZV) skin infections share so many histological similarities that distinguishing between them may prove to be impossible. We developed and characterized a new monoclonal antibody, VL8, IgG kappa isotype, directed to the VZV envelope glycoprotein gpI. Immunohistochemistry with VL8 appeared highly sensitive and specific on formalin-fixed paraffin-embedded biopsies and a clear-cut distinction between HSV and VZV infections was possible. The pattern of VL8 immunolabelling in VZV infections was strikingly different from that found in HSV infections studied with polyclonal antibodies to HSV I and II. Double immunolabelling revealed the VL8 positivity of sebaceous cells, endothelial cells, Mac 387- and CD68-positive monocyte-macrophages, and factor XIIIa-positive perivascular, perineural and interstitial dendrocytes. Intracytoplasmic VL8 labelling of endothelial cells and perivascular dendrocytes was found at the site of leukocytoclastic vasculitis.

CD68 and Factor XIIIa expressions in granular-cell tumor of the skin

Immunohistochemical and electron microscopic studies support a Schwann cell origin for most of the granular-cell tumors of the skin. We studied 9 granular-cell tumors by immunohistochemistry, using antibodies to CD68, S-100 proteins, factor XIIIa, L1 antigen, desmin and vimentin. The CD68 monocyte-macrophage-associated lysosomal antigen was expressed in granular cells which however had no Mac 387 reactivity. The satellite fibroblasts were factor XIIIa-positive similarly to dendrocytes and perineurial cells. Our study reveals the lack of specificity of CD68 antibody to identify macrophages. It also presents granular cell tumor of the skin as an exception in the group of schwannomas by the presence of factor XIIIa-positive cells inside the neoplasm.

Neutrophilic Eccrine Hidradenitis. A Case Report

Neutrophilic eccrine hidradenitis (NEH) is a rare neutrophilic dermatosis occurring most frequently during induction chemotherapy for a variety of malignancies. We report a case of NEH in a 41-year-old woman with acute myeloblastic leukemia under daunorubicin, cytarabine and etoposide chemotherapy. She developed red, tender and painful nodules on a shoulder. The lesions resolved spontaneously. Histological examination is mandatory as the clinical presentation of this dermatosis is highly polymorphic. Leukemia cutis, sepsis, deep fungal infection and Sweets syndrome must be excluded as these implicate different therapies.

Dermal dendrocytes and photochemotherapy

We studied the fate of dermal dendrocytes in patients treated with psoralens and ultraviolet light by combining immunohistochemistry and computerized image analysis. Factor-XIIIa-positive dermal dendrocytes were found to be altered in these patients. When compared with controls, dermal dendrocytes were often increased in number and had an uneven size and tissue distribution. Their cytoplasm was occasionally fragmented. These changes were more pronounced when early photosclerosis was present. The alterations described probably reflect vascular changes, and may be responsible for immunomodulating actions and disorder of the connective tissue structure induced by ultraviolet light.

The HLA‐dermatosis connection

A number of dermatological diseases are associated with distinct HLA types. These associations vary in different populations and ethnic groups. HLA determination can be related to different disease courses, various anatomical predilection sites and can be used as a diagnostic tool. However, the pathogenic role of HLA in susceptibility to specific dermatological diseases often remains unclear.