The slide is on the scope, the tray previews in two hours, and the inflammatory biopsy in front of you could be chronic dermatitis, early mycosis fungoides, or something you have never seen signed out cleanly. Vague descriptive diagnoses — nonspecific chronic dermatitis, atypical melanocytic proliferation, see comment — do not fail the slide; they fail the patient whose surgery, staging, and treatment depend on what your report says. This handbook installs a structured five-part diagnostic framework into every major entity in skin pathology, so every sign-out begins with a locked low-power gestalt, ends with a specific Decision Anchor, and names the dangerous look-alike before it names you. • The Sign-Out Signature System — a five-part callout at every major entity giving you the low-power lock, high-power confirm, trap mimics, and single Decision Anchor that closes the diagnosis • Reaction patterns decoded — spongiotic, psoriasiform, interface, vesiculobullous, granulomatous, vasculitic, and panniculitic patterns each built into a bench-side discriminator sequence • The melanocytic minefield navigated — maturation, pagetoid spread, PRAME, salt-split skin, and the recurrent nevus trap presented as an integrated decision framework • Desmoplastic melanoma caught — the most commonly missed melanoma subtype flagged by its scar-like low-power appearance, with SOX10 as the mandatory lineage step • The spindle cell differential resolved — a structured IHC panel separating AFX, desmoplastic melanoma, spindle cell SCC, and leiomyosarcoma on sun-damaged skin • Panniculitis without a missed lymphoma — every lobular lymphocytic panniculitis driven to immunohistochemistry before SPTCL is excluded • The Sign-Out Signature Master Atlas — every signature from all twenty chapters indexed by reaction pattern and histologic finding for rapid retrieval at the scope Written for pathology residents, dermatopathology fellows, and surgical pathologists who sign out skin biopsies and refuse to default to a descriptive non-diagnosis when a specific answer is available. Bring this to the scope — and sign out with confidence every time.
