Ch. 1 - Normal anatomy Flashcards
Scalp skin
Numerous follicles extending into the panniculus with associated sebaceous glands and arrector pili muscle
Facial skin
Thin epidermis, basket-weave stratum corneum, demodex mites.
Truncal skin
Thick dermis, fewer adnexal structures but enveloped with projections of fat.
Areolar skin
Slight acanthosis, basilar hyperpigmentation, apocrine glands, smooth muscle bundles.
Acral skin
Compact eosinophilic stratum corneum and slight papillomatosis on dorsal surfaces
Volar skin
Compact eosinophilic hyperkeratosis with underlying stratum lucidum. Eccrine glands & meissner/pacinian corpuscles. No hair.
Eyelid
No hair follicles or stratum corneum, but goblet cells are present.
Mucosa
Absent granular layer, glycogenated keratinocytes, smooth muscle bundles and dilated vessels.
Nasal turbinate
Erectile tissue with fibrous septa, mucous glands, and vascular sinusoids
Fetal skin
Stellate and spindled fibroblasts (mesenchyme). Densely cellular.
Hair (infundibulum)
Most superficial (to sebaceous gland insertion). Keratinizes in the pattern of the normal epidermis with a granular layer. Intraepidermal portion is the “acrotrichium”
Hair (isthmus)
From sebaceous gland to insertion of arrector pili. Keratin formed without granular layer (trichilemmal keratinization). Inner root sheath lost at this level.
Hair (stem)
From insertion of arrector pili to Adamson’s fringe (where hair cornifies). Only present in anagen hairs.
Hair (bulb)
From Adamson’s fringe to base of follicle. Matrix, Supramatrix, and Keratogenous zones.
Nail anatomy (key features)
Nail plate, nail bed, framing portion, ensheathing portion (eponychium, hyponichium, solehorn, bed horny layer)
Cuticle
Visible cuticle (eponychium) is visible thick keratinous material that borders the proximal nail fold.
True cuticle is beneath the eponychium. Sometimes visible as flakes of keratinous material.
Hyponychium, solehorn.
Hyponychium: Space, epithelium, and keratinous material ventral to the nail plate
Solehorn: Subungual white/colorless keratin
Lunula
Visible portion of nail matrix
Types of nail keratinization
Onychokeratinization (no granular layer, hard keratin)
Onycholemmal keratinization (ventral part of proximal nail fold)
Epidermoid keratinization (Dorsal and lateral proximal nail folds)
Dermal dendrocyte
Macrophage-type APCs in the dermis. Usually XIIIa+, S-100+
Giant cell subtypes
Foreign-body: Haphazard nuclei
Langerhans: Wreath-shape nuclei
Osteoclast-like: Haphazard and eccentric nuclei, deep pink and scalloped cytoplasm
Touton: Wreath-shape nuclei with foamy peripheral cytoplasm
Ringed siderophage: Touton giant cell with hemosiderin (seen in fibrous histiocytoma)
Langerhans cell
Dendritic APC in epidermis and dermis. Reniform nucleus. CD1a+, S100+, langerin+. Contains birbeck granules.
Mast cell
“Fried-egg” round and bluish cell with metachromic granules.
