This issue of Pathology Case Reviews focuses on some of the major topics in inflammatory dermatopathology. Although inflammatory skin lesions are certainly not the bulk of the specimens received by the practicing general pathologist, the final words on the diagnostic line can have enormous impact. In many instances, the diagnosis by the pathologist is heavily dependent on the clinical input. As there are only a limited number of patterns of inflammation combined with a limited number of types of inflammatory cells, considerable histologic overlap exists in many diagnoses. A meaningful signout relies on the clinical correlation.
To reinforce the significance of the clinical input, this issue begins with an article by Dr. Rencic, a staff dermatologist and clinical instructor, who reviews the clinical presentations of the various entities presented in the articles that follow. The appropriate treatment plan can be instituted immediately with an informed diagnosis. Not to be too misled, there are certainly many instances in which the clinical differential diagnosis can not be sorted out based on the histologic picture and the frustration of the clinician, as well as the patient, who must wait for the lesions to resolve or further develop, is well understood.
Dr. Lynch follows with the presentation of several cases that have the initial histologic impression of pseudoepitheliomatous hyperplasia; some of which are simply that and some of which have underlying disease. The cases presented illustrate, once again, not only the importance of clinical information, but also the importance of a proper biopsy. The clinicians may feel satisfied that they have obtained a deep biopsy, only to get back a report revealing pseudoepitheliomatous hyperplasia, transected at the base. It leaves one to ponder what may lie deeper in the dermis. Some of the cases presented drive home this point.
The vast field of neutrophilic dermatosis is addressed by Dr. Moresi, who relates the striking histologic similarity in these entities that have a noninfectious etiology. Systemic manifestations are common in this group and often have overlapping clinical features.
Dr. Wilkerson presents a very interesting case report of a neutrophilic dermatosis, suspected clinically to be Sweet syndrome and thought initially, on histologic features, to be consistent with Sweet syndrome. In this case, the clinical information was misleading and diagnosis depended on the astute observations given to the histology as well as to the proper histologic evaluation of a neutrophilic dermatosis.
To avoid the pitfalls of relying on immunohistochemical markers, Drs. Kahn and Horenstein elucidate the significance of a CD30-positive infiltrate. This marker is well known in the hematopoietic evaluation of entities such as anaplastic large cell lymphoma, Hodgkin disease and transforming mycosis fungoides. This article reminds the pathologist to be aware of the reactive and nonmalignant infiltrates in which CD30 expression may also be seen. Additionally, the article points out increased expression of CD30 in HIV-positive patients, once again reinforcing the importance of clinical information.FIGURE
Rheumatologic diseases are associated with numerous cutaneous manifestations. In fact, cutaneous lesions are typically the presenting symptom in such entities as lupus erythematosus and dermatomyositis. Dr. Selim outlines the clinical presentation and histologic findings of these cutaneous manifestations.
Finally, Dr. Hiatt addresses a subclass of blistering disorders caused by autoantibody production. These antibodies are directed against adhesion molecules involved in the keratinocyte-keratinocyte interaction as well as against some of those proteins involved in the keratinocyte-basement membrane mechanism of adhesion. Due to the limited number of interactions involved, the histologic picture alone may not be diagnostic. However, a combination of histology, immunofluorescence studies and clinical information can help elicit the proper diagnosis.
A common theme throughout the case presentations is the usefulness of the appropriate biopsy and a thorough clinical history. Together, with an informed pathologist at the oculars, a meaningful diagnosis can be rendered. I hope the following articles are informative in this respect.