This volume seeks to assist a microscopist, by virtue of algorithmic method based largely on analysis of architectural pattern (silhouette) and of specific differentiation of neoplastic cells. It is illustrated with photomicrographs that are presented in repeatable sequence from scanning through intermediate to high magnification. Included is glossary of terms. Main chapter headings: 2. Normal structures of skin adnexa 3. Principles of diagnosis 4. Proliferations with infundibular differentiation 5. Proliferations with follicular differentiation 6. Proliferations with sebaceous differentiation 7. Proliferations with apocrine differentiation 8. Proliferations with eccrine differentiation 9. Proliferations with combined adnexal differentiation 10. Verrucae vulgares, including tricholemmoma and inverted follicular keratosis 11. Induction of adnexal strucures by abnormalities of connective tissue 12. Cysts, including infundibular, isthmic-catagen, and apocrine gland types. .