Skin
Evaluation of skin pathology specimens requires a wide range of diagnostic skills including an integration of dermatological clinical examination together with a systematic histopathologic evaluation of both reactive and neoplastic conditions.
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Skin Carlos A. Torres-Cabala, Michael T. Tetzlaff, Priyadharsini Nagarajan, Doina Ivan, Jonathan L. Curry, Phyu P. Aung, and Victor G. Prieto
Introduction
Handling and Processing of Specimens
Evaluation of skin pathology specimens requires a wide range of diagnostic skills including an integration of dermatological clinical examination together with a systematic histopathologic evaluation of both reactive and neoplastic conditions. This chapter reflects the complex cellular composition of the skin. Neoplastic conditions are divided according to cell of origin in epidermal, adnexal, melanocytic, neural (including Merkel cell carcinoma), soft tissue, and hematolymphoid proliferations. Emphasis is given to common malignant conditions, but unusual and rare entities are included for adequate differential diagnosis. Benign skin tumors are also discussed, and, when pertinent, reactive inflammatory conditions are described—particularly those encountered in patients being treated for either cutaneous or extracutaneous malignancies. Awareness of clinical presentation is crucial for many dermatological inflammatory conditions; at the same time, careful selection and interpretation of immunohistochemical and molecular studies are required for an accurate pathological diagnosis of cutaneous tumors.
Priyadharsini Nagarajan
Carlos A. Torres-Cabala and Michael T. Tetzlaff contributed equally with all other contributors. C. A. Torres-Cabala (*) · M. T. Tetzlaff · P. Nagarajan D. Ivan · J. L. Curry · P. P. Aung · V. G. Prieto Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA e-mail: [email protected]
Dermatopathology specimens encompass small specimens such as incisional biopsies, core needle biopsies, skin shave, and punch biopsies as well as larger elliptical or circular excisions of variable sizes and shapes. The objectives of processing of these specimens are to optimally present the lesional area and relevant margins for histopathologic evaluation while maintaining its anatomic relationship to the surrounding uninvolved area, if any, and to allow accurate measurement of the tumor dimensions as well as closest distances to margins [1, 2], to render the tissue optimal for application of several ancillary techniques, and to preserve the tissue for prolonged storage. In almost all dermatopathology cases, with the exception of biopsies performed for alopecia, the skin tissue should be oriented perpendicular to the surface of the epidermis on the glass slide [3–8]. This is achieved by embedding the sections on edge. Ideally, not more than 2–3 tissue pieces with approximate thickness of 3–4 mm should be submitted per cassette. This will ensure optimal fixation and processing as well as proper embedding of the tissue in the same plane of the paraffin block, so that the spatial relationship between the epidermis, dermis, adnexal structures, and subcutaneous fibroadipose tissue can be appreciated and tumor thickness can be measured accurately. Most specimens are fixed in neutral bu
