The basics: Diagnostic terms, skin anatomy, and stains

Loss of cell–cell adhesion

Increase in thickness of the epidermis

Regular (all rete pegs descend to the same level) or irregular (rete pegs descend to different levels in the papillary dermis)

Atypical nuclei (abnormal size, shape, staining) and pleomorphism (variation in nuclear characteristics)

“Programmed cell death”

“Dead red” keratinocytes with pyknotic nuclei

Although the term is often applied to any necrotic or dyskeratotic keratinocyte, it is best reserved for physiologic programmed cell death or pathologic processes that produce death through a similar pathway

Branching, often refers to rete or vasculature

Collections of eosinophilic material seen in sporotrichosis

Also refers to star-shaped intracytoplasmic inclusions seen in giant cells of sarcoidosis or berylliosis or other granulomatous processes

Decrease in thickness of epidermis

Destruction of epidermis by dissolution of cell attachments and intracellular edema

Pale pink linear basement membrane material within epidermis, seen in porphyria cutanea tarda

Represents degenerated type IV collagen

Pink, globular remnants of keratinocytes

Collagen fibers surrounded by histiocytes/spindle cells (collagen balls)

Forty-five–degree angle parakeratosis in a column above a focus with a diminished granular layer and underlying dyskeratotic cells

Corps ronds = rounded nucleus with halo of pale to pink dyskeratotic cytoplasm

Grain = dark blue flattened nucleus surrounded by minimal cytoplasm

Dyskeratosis = abnormal, individual-cell keratinization

Also known as the Lipschutz body

Intranuclear pink inclusions of herpesvirus infection

Intranuclear pink inclusions of adenovirus and poliovirus infection

Serum/fluid with inflammatory cells/debris in stratum corneum

Intracytoplasmic collections of bacteria seen in granuloma inguinale

Intracytoplasmic pink masses of immunoglobulin that invaginate into the nucleus of plasma cells and appear to be intranuclear

Loss of normal rete pattern

Spongiosis with eosinophils in the epidermis

Coarse, irregular hypergranulosis associated with disruption of cell membranes

Associated with keratin 1 and 10 mutations

Lymphocytes in epidermis with relative absence of spongiosis; term usually reserved for mycosis fungoides

Partial thickness loss of epidermis

Lymphocytes in the epidermis with associated spongiosis; term usually used when discussing spongiotic dermatitis

Papillary dermis retains an undulating pattern (often used to describe porphyria cutanea tarda)

Collagen encrusted with major basic protein from eosinophils

Lipid-laden histiocyte

Alteration of hair sheath anatomy by pools of mucin

Composed of granulomas (collections of histiocytes)

Uninvolved area of dermis beneath the epidermis or adjacent to a hair follicle (border zone)

Eosinophilic inclusions of smallpox

Intracytoplasmic oval, pink inclusions of molluscum infection

Increased/decreased granular layer

Increased/decreased melanin pigment

Generally refers to the dermoepidermal junction

Dull pink to amphophilic basement membrane material within the epidermis in a Spitz nevus

Fragmentation of neutrophils (leukocytoclasis). (If neutrophils resemble ants with segmented bodies, then karyorrhexis resembles dismembered ants and scattered ant heads)

Keratinocytes with clear cytoplasm and shrunken “raisinlike” pyknotic nuclei

Intracytoplasmic collections of amastigotes in leishmaniasis

Elongated bulbous rete

Proliferation predominantly along the dermoepidermal junction

Fragmentation of neutrophils, also referred to as karyorrhexis

Interface dermatitis with destruction of the basal layer and Civatte body formation ( Fig. 1.7 and Fig. 1.19 )

A bandlike infiltrate, generally composed predominantly of lymphocytes, located at the dermoepidermal junction

Brown, round structure resembling overlapping copper pennies

Divide by septation, resembling a hot-cross bun

The property of staining a different color from the stain itself (i.e., the purple color of mast cell granules with the blue stain methylene blue)

Intracellular and extracellular calcified, concentric circular structures, seen in malakoplakia

Collection of neutrophils in the stratum corneum, as seen in psoriasis

Pale-staining, smudged, necrotic collagen

Inclusions within neurons seen in rabies infection

Stratum corneum without retained nuclei

Large cells with abundant cytoplasm within the epidermis

Buckshot scatter of atypical cells within the epidermis

Picket fence–like arrangement at the periphery

Structure that resembles the whorl of plump mesenchymal cells normally present in the hair papilla (seen in trichoblastoma and trichoepithelioma)

Exophytic fingerlike projections

Stratum corneum with retained nuclei

Melanin within dermal macrophages and free within the dermis

Variation in nuclear size/shape

Extracellular laminated, calcified structures seen in meningioma, papillary thyroid carcinoma, and ovarian carcinoma

Prominent acanthosis of the adnexal epithelium and epidermis, mimics squamous cell carcinoma

Often associated with trapping of elastic fibers

Keratin-filled cystic structure that is the result of cutting through invaginations of the stratum corneum (similar to a horn cyst, but connects to the surface)

Destruction of epidermis with cell membranes remaining in a netlike pattern

Network of interconnecting strands (netlike)

Intracytoplasmic pink collections of immunoglobulins in plasma cells, seen in rhinoscleroma and other conditions with many plasma cells

Laminated calcified structure seen in sarcoidosis

Cells with barely visible outlines of nuclei

Neutrophils in the stratum spinosum, associated with spongiosis at the periphery (typical of psoriasis)

Intercellular edema in epidermis with stretching of cell–cell junctions ( Fig. 1.14 )

Loss of cuboidal/columnar basal cells, with deepest layer now being polyhedral, pink squamous cells

Circular whorls of squamous cells

Cartwheel or loosely whorled pattern

Formation of clear spaces within the basal layer

Structure composed of two nuclear palisades enclosing pink cytoplasmic processes, seen in schwannoma

Projection of papillary dermis covered by a layer of epidermal cells into a cavity