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Common terms & patterns

Authors: Carina Dehner, M.D., Ph.D., Louis P. Dehner, M.D.

Editorial Board Member: Jonathan D. Ho, M.B.B.S., D.Sc.

Last author update: 30 January 2023

Last staff update: 30 January 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Spongiotic dermatitis, psoriasiform dermatitis

Table of Contents

Cite this page: Dehner C, Dehner LP. Common terms & patterns. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorcommonterms.html. Accessed December 25th, 2024.

Definition / general

This topic represents an overview of common terms and microscopic findings of the most frequently seen reaction pattern in dermatopathology

Terminology

Acantholysis:
- Separation of cell - cell connections (desmosomes) between keratinocytes leading to single, rounded keratinocytes
- Seen in pemphigus variants and related disorders
Acanthosis:
- Thickening of epidermis
- Elongated rete ridges usually extend into dermis
- Can be regular (all rete pegs at roughly the same level) or irregular (rete pegs at different levels of the papillary dermis)
Anagen:
- Hair during growth phase
Anaplasia:
- Atypical nuclei (abnormal in size and shape) and pleomorphism (variation in nuclear characteristics)
Asteroid body:
- Collections of eosinophilic material in sporotrichosis or star shaped inclusion in sarcoidal giant cells / other granulomatous processes
Atrophy:
- Epidermal:
  - Decreased thickness due to reduced numbers of keratinocytes
  - Epidermis may appear flat at its base with loss of rete ridge pattern
  - May occur after inflammation / certain topical treatments
- Dermal:
  - Thinning of dermal layer due to loss of collagen / elastin
  - May occur after steroids and atrophodermas
Banana bodies:
- Yellow-green, banana shaped fibers in the dermis; can be due to exogenous or endogenous causes
Basal vacuolar degeneration:
- Also known as liquefactive / hydropic degeneration
- Small vacuoles resembling bubbles in the basal layer
- Often associated with individually necrotic keratinocytes
- May or may not have an associated band of infiltrate obscuring the dermoepidermal junction
- Associated with vacuolar / lichenoid interface dermatitis (e.g., cutaneous lupus, erythema multiforme, lichen planus)
Basement membrane:
- Thin membranous layer of extracellular matrix which is separating the epidermis from the dermis
Birefringence:
- Optical capacity of a material with a refractive index that depends on polarization and propagation of direction of light
Blister:
- Fluid filled skin lesions
- May result from separation of keratinocytes (intraepidermal blisters) or loss of adhesion between the epidermis and the underlying dermis (subepidermal blisters)
- Examples of diseases commonly associated with blisters include autoimmune bullous dermatoses, interface dermatitis, spongiotic dermatitis and some viral and bacterial infections
Bullae:
- Fluid filled lesion > 1 cm (= large blister)
Calcinosis:
- Cutaneous deposition of insoluble calcium in response to damage, metabolic derangements or undetermined etiology
Catagen:
- Hair during regressive phase
Caterpillar bodies:
- Eosinophilic bodies present within the roof of the blister formed in porphyric bullous eruptions, such as porphyria cutanea tarda
Civatte / colloid bodies:
- Globular residue of apoptotic keratinocytes
- Typically pink in color
- Referred to as Civatte bodies when present within the epidermis and as colloid bodies when in the papillary dermis
- Classically described in lichen planus but may be seen in all causes of interface / lichenoid dermatitis
Comedo:
- Dilated follicular infundibulum filled with keratin, lipid (not visible with standard stains) and often basophilic debris
- Bacterial colonies may be present
- Classical lesion in acne vulgaris
Cornoid lamellae:
- Layers of parakeratosis often in a ~45° angle overlying an area of diminished granular layer with dyskeratotic cells present at the base
- Classically seen in porokeratosis variants
Cowdry bodies:
- Cowdry A: intranuclear inclusion in herpes simplex virus
- Cowdry B: intranuclear inclusion in cytomegalovirus, adenovirus, poliovirus
Crust:
- Hyperkeratosis (often parakeratosis) with inspissated serum with or without Inflammatory cells (= wet scale)
Cyst:
- Encapsulated cavity or sac lined by true epithelium
DEJ:
- Dermoepidermal junction
Dermal papilla (hair):
- Layer that is located at the base of the hair follicle
Desmosome:
- Adhesion molecule between two cells
Diffuse infiltrate:
- sheets of inflammatory ells diffusely infiltrating dermis
Donovan body:
- Rod shaped, oval organisms within histiocytes in granuloma inguinale
- Characteristic bipolar staining pattern gives safety pin appearance
- Highlighted by Warthin-Starry and Giemsa stains
Dutcher body:
- Spherical, intracytoplasmic immunoglobulin inclusions that appear intranuclear due to folding into the nucleus of plasma cells
- Seen in plasmacytoma
Dyskeratosis:
- Abnormal, premature keratinization of keratinocytes below granular cell layer
- Often have brightly eosinophilic cytoplasm with or without a pyknotic nucleus
Effacement:
- Synonymous with consumption of the epidermis
- Refers to thinning of the epidermis / loss of rete ridges
- Commonly seen in melanoma
Elastolysis:
- Defect in elastic fibers leading to atrophy, skin laxity
Elastorrhexis:
- Fragmentation of elastic fibers; systematic elastorrhexis seen in pseudoxanthoma elasticum
Elastosis:
- Degenerative changes in elastic fibers (increase in abnormal elastin) leading to loss of elastic quality of the dermis
Epidermolysis:
- Alteration of granular layer with perinuclear clear spaces, swollen and irregular keratohyalin granules, increased thickness of granular layer
- Different from acantholysis
- Classically seen in epidermolytic ichthyosis and keratodermas but may be seen in epidermal nevi, isolated keratoses and incidentally
Epidermotropism:
- Atypical individual cells present in epidermis without significant spongiosis
- Most commonly refers to atypical lymphocytes in cutaneous T cell lymphomas but can be seen in other malignant neoplasms, including melanoma and metastatic deposits
Erosion:
- Discontinuity of skin causing partial loss of epidermis
Excoriation:
- Deep scratch with abrupt loss of epidermis without full thickness loss at an ulcer
- Excoriation may result in partial or full thickness epidermal loss (erosion versus ulcer)
- Often self induced
Exocytosis:
- Inflammatory cells migrating into the epidermis (commonly seen in spongiotic dermatitis)
- Lymphocytes, neutrophils and eosinophils most commonly seen
Festooning:
- Undulating pattern of the dermal papillae
- Commonly seen underneath bullae / blisters (e.g. in porphyria cutanea tarda / subepidermal autoimmune bullous diseases)
Fibrinoid necrosis:
- Necrosis associated with vascular damage
Fibrosis:
- Increased amount of fibroblasts forming a scar or skin thickening
Flame figure:
- Deposition of eosinophil granules from degranulated eosinophils and nuclear debris on dermal collagen fibers with or without surrounding histiocytes
- Classically seen in Wells syndrome (eosinophilic cellulitis) but may be seen in a variety of eosinophil rich diseases
Foam cell:
- Histiocyte whose cytoplasm is replaced by variably sized lipid vacuoles
- Commonly seen in xanthoma variants, lipidized dermatofibromas and some histiocytoses
Follicular plugging:
- Process of abundant hyperkeratotic material plugging up follicular ostia
Globi:
- Amphophilic collection of mycobacteria, classically seen in leprosy
Granuloma:
- Collection of macrophages forming a cluster / round structure in response to certain types of inflammation (foreign material, microorganisms, etc.)
Grenz zone:
- Thin layer of uninvolved dermis directly beneath the epidermis, separating it from an inflammatory cell infiltrate or tumor
- Grenz zones classically seen in granuloma faciale, leukemia cutis, dermatofibromas, lepromatous leprosy and solar elastosis
Hemidesmosome:
- Adhesion molecule between cell and basal lamina
Henderson-Patterson body:
- Cytoplasmic viral inclusion bodies often filling cup shaped cavity space in molluscum contagiosum (molluscum bodies)
Horn (cutaneous horn):
- Massive vertically oriented hyperkeratosis (parakeratotic, orthokeratotic or mixed) most commonly overlying a keratinocytic neoplasm
- Importance lies with the lesion which underlies the horn which may be malignant in a significant minority
Horn cyst:
- Hyperkeratotic epithelial structure presumably due to abrupt complete keratinization
Hypergranulosis:
- Thickening of the stratum corneum
Hyperkeratosis:
- Thickened cornified layer (stratum corneum)
- Keratin may be abnormal
- Either orthokeratotic (typically compact keratin with no nuclei) or parakeratotic (nuclei in cornified layer)
Inferior follicle:
- Inferior segment of the follicle from the bulge to the base of the follicle
Infundibulum:
- Upper segment of the hair follicle
Interface dermatitis:
- Pattern of inflammatory dermatitis characterized by basal layer vacuolation with or without a band of inflammation obscuring the dermoepidermal junction
- When band-like lymphocytic infitlrate present, referred to as lichenoid interface or lichenoid dermatitis
Isthmus:
- Segment between the sebaceous gland duct opening and the hair bulge
Kamino bodies:
- Eosinophilic bodies associated with spitz nevi
Koilocyte:
- Keratinocyte that underwent structural changes due to viral infection
Lentiginous:
- Linear pattern of melanocytic proliferation within epidermal basal cell layer
Leukocytoclasis:
- Vascular karyorrhexis of degenerating neutrophils is a feature of neutrophilic vasculitis (also called leukocytoclastic vasculitis)
Leukocytoclastic vasculitis:
- Inflammatory reaction of blood vessels including fibrinoid changes within the vessel walls
Lichenification:
- Thick, rough skin with prominent skin markings usually due to repeated rubbing
- Associated with hyperkeratosis
Lichenoid dermatitis:
- Inflammatory pattern characterized by basal vacuolar change and a band of inflammatory cells at the dermo - epidermal junction
Lichenoid infiltrate:
- Band-like lymphocytic infiltrate at the dermoepidermal junction
Macule:
- Flat lesion less than 1.0 cm
Medlar body:
- Also known as sclerotic bodies
- Brown, round fungal cell in between yeast and hyphal state with the appearance of copper pennies
- Diagnostic for chromoblastomycosis
Michaelis-Gutmann body:
- Round, calcified structures located within the cytoplasm of histiocytes in malakoplakia
- Stain with Perls stain for iron and von Kossa for calcium
Mikulicz cells:
- Large foamy histiocytes containing rods of klebsiella rhinosclermomatis in rhinoscleroma
Munro microabscess:
- Neutrophilic collections in the stratum corneum
- Classically seen in psoriasis
Necrobiosis:
- Altered / necrotic collagen
- Seen in granuloma annulare and other necrobiotic lesions
Nevus:
- Often used to refer to a benign tumor of melanocytes but may also refer to a hamartomatous lesion of any component of the skin (epidermis, dermis, blood vessels etc.)
Nodular inflammation:
- Inflammatory cells forming nodular collections
Nodule:
- Solid lesion (> 1 cm) whose vertical dimension is greater than its horizontal
Oncholysis:
- Separation of the nail plate from the underlying nail bed
- Associated with psoriasis, trauma, onychomycosis, thyrotoxicosis and phototoxic drug ingestion
Owl eye inclusion:
- Term used to describe a cells infected by cytomegalovirus
Pagetoid spread:
- Single malignant cells involving the epidermis
Panniculitis:
- Lobular:
  - Inflammation of fat involving predominantly the fat lobules (e.g., erythema induratum, pancreatic panniculitis, etc.)
- Septal:
  - Inflammation of fat involving predominantly the septae in between the fat lobules (e.g., erythema nodosum)
Papillary dermal edema:
- Extracellular accumulation of fluid leading to thinning of the dermis
Papillary mesenchymal body:
- Structures associated with follicular differentiation; can serve as helpful clue in follicular type adnexal neoplasms, such as trichoepithelioma / trichoblastoma
Papillomatosis:
- Finger-like undulation of the epidermis with upward expansion of dermal papillae
- May have associated epidermal hyperplasia
Papule:
- Raised lesion < 1 cm
Parakeratosis:
- Retention of nuclei in the stratum corneum
- Normal for mucous membranes without stratum granulosum
Parasitized macrophages:
- Macrophages infected by parasites present within their cytoplasm (e.g., in leishmaniasis)
Patch:
- Flat lesion > 1 cm
Pautrier microabscess:
- Collections of atypial lymphocytes involving the epidermis; seen in mycosis fungoides
Periadnexal inflammation:
- inflammatory cells predominantly surrounding the adnexal structures
Perivascular inflammation:
- Inflammatory cells predominantly surrounding vasculature
Plaque:
- Raised, relatively flat topped lesion > 1 cm
Poikiloderma:
- Combination of atrophy, telangiectasia and pigmentary changes
Pseudoepitheliomatous hyperplasia:
- Exaggerated acanthosis of the epidermis mimicking squamous cell carcinoma
- Commonly seen in the epidermis overlying prior procedure sites, chronic inflammation, granular cell tumor, blastomycosis
Psoriasiform epidermal hyperplasia:
- Acanthosis of the epidermis with regular elongation the rete ridges
Purpura:
- Extravasation of red blood cells into the skin or mucous membranes with or without inflammation
Pustule:
- Intraepidermal or subepidermal vesicle or bullae filled with neutrophils
Scale:
- Dry, horny, plate-like excrescence corresponding to hyperkeratosis
- Usually due to imperfect cornification
Schaumann body:
- Laminated calcified structure
- Seen in sarcoidosis but rare in skin lesions
Sclerosis:
- Excess connective tissue with decreased amount of fibroblasts
Shadow cells:
- Cells without a nucleus due to prior cell death
Sinus:
- Tract connecting cavities to each other or to the surface
Spongiform pustule of Kogoj:
- Collection of neutrophils within the stratum spinosum
- Associated with spongiosis at the periphery (e.g. seen in psoriasis)
- Seen in psoriasis, including pustular variants
Spongiosis:
- Intraepidermal edema causing splaying apart of keratinocytes in stratum spinosum (resembling a sponge)
- Intercellular adhesion proteins (desmosomes) often visible
- Vesicles due to shearing of desmosomes
Squamous eddies:
- Whorled profiles composed of keratinocytes (e.g. seen in inverted follicular keratoses)
Storiform:
- Growth pattern consisting of spindle cells arranged in a cartwheel-like pattern
- Classically seen in dermatofibrosarcoma protuberans (DFSP)
Telogen:
- Hair during resting phase
Ulceration:
- Discontinuity of skin causing complete loss of epidermis and possible loss of dermis with accompanying surface fibrin deposition or exudate with or without granulation tissue response
Verocay body:
- Structure composed of 2 nuclear palisades with central eosinophilic cytoplasmic processes
- Classically seen in schwannoma
Vesicle:
- Fluid filled lesion < 1 cm
Von Hansemann cells:
- Large macrophages containing Michaelis-Gutmann bodies seen in malakoplakia
Wheal:
- Itchy, transient, elevated area with variable blanching and erythema
- Due to dermal edema

Granulomatous dermatitis

Similar pattern seen in various clinical settings
- Sarcoidosis
- Necrobiosis lipoidica (associated with diabetes mellitus)
- Granuloma annulare (localized, generalized, etc.)
- Palisaded neutrophilic and granulomatous dermatitis
- Granulomatous reaction to foreign material

Contributed by Carina Dehner, M.D., Ph.D.

Perivascular and interstitial inflammation

Infections

Bacterial
- Impetigo:
  - Nonbullous or bullous forms
  - Gram positive cocci are the trigger
- Staphylococcus scalded skin syndrome:
  - Sterile subcorneal split of epidermis
  - Driven by toxins from certain Staphylococcus aureus strains
- Rhinoscleroma:
  - Diffuse inflammatory infiltrate underlying submucosa, Mikulicz cells present
  - Trigger: Klebsiella pneumoniae
- Erythrasma:
  - Erythematous intertriginous patches
  - Triggered by Corynebacterium minutissimum infection
Viral
- Herpes virus:
  - Multinucleated keratinocytes with chromatin margination and molding
  - Mucosal sites (HSV1 / 2) or dermatome distribution (varicella zoster virus)
- Epstein-Barr virus (EBV):
  - Infectious mononucleosis, oral hairy leukoplakia, Gianotti-Crosti syndrome
  - EBV virus can be detected by in situ hybridization
- Cytomegalovirus:
  - Large, intranuclear inclusions with halo
- Molluscum contagiosum:
  - Molluscum bodies
  - Trigger: poxvirus
Spirochetes
- Syphilis:
  - Psoriasiform hyperplasia, mixed pattern dermatitis
  - Treponema pallidum
Fungal
- Dermatophytosis:
  - Neutrophils in stratum corneum sandwich sign: parakeratosis or compact orthokeratosis underlying basket weave type stratum corneum
- Majocchi granuloma:
  - T. rubrum
  - Fungi surrounding degenerate hair shafts
- Pityriasis (tinea) versicolor:
  - Malassezia
  - Need to see spores and hyphae in stratum corneum
- Blastomycosis:
  - May induce pseudoepitheliomatous hyperplasia
Arthropods / parasites
- Demodex:
  - Commonly seen, mostly incidental
  - If exuberant, can induce pathologic changes leading to dry eye, chalazion, etc.
- Scabies:
  - Potassium hydroxide preparation (KOH prep) can be done on bed site
  - Itchy for years

Contributed by Carina Dehner, M.D., Ph.D.

Eggshells of scabies

Mixed pattern dermatitis

Lichenoid dermatitis

Lichenoid dermatitis, with or without interface
- Band-like inflammation and basal vacuolar degeneration (lichen planus, etc.)
Interface changes without lichenoid inflammation (discoid lupus, erythema multiforme)
- Basal vacuolar degeneration and dyskeratotic keratinocytes only (erythema multiforme)
- Basal vacuolar degeneration and dyskeratotic keratinocytes at the dermoepidermal junction + superficial and deep perivascular, periadnexal inflammation and increased dermal mucin (discoid lupus erythematosus)

Contributed by Carina Dehner, M.D., Ph.D.

Lichenoid interface dermatitis

Panniculitides

Septal panniculitis
- Erythema nodosum
Lobular panniculitis: diverse group associated with rheumatoid arthritis, gout (Arch Dermatol 1998;134:501)
- Pancreatic panniculitis: lobular fat necrosis with saponification and ghost cells
- Erythema induratum: prominent fat necrosis, histiocytes, giant cells, granulomas, vasculitis
- Lupus panniculitis: may show lymphoid follicles
- Sclerosing panniculitis (lipodermatosclerosis)

Contributed by Carina Dehner, M.D., Ph.D.

Saponification and ghost cells

Perivascular dermatitis

Wide spectrum of diagnoses
- Superficial: dermal hypersensitivity with or without eosinophils, urticaria
- Superficial and deep: arthropod bite, connective tissue diseases

Psoriasiform dermatitis

Psoriasiform hyperplasia (e.g. psoriasis, lichen simplex chronicus, pityriasis rubra pilaris, etc.)

Contributed by Carina Dehner, M.D., Ph.D.

Psoriasiform hyperplasia

Alternating parakeratosis and orthokeratosis

Sclerosing dermatitis

Localized scleroderma (morphea)
Guttate morphea
Systemic sclerosis

Contributed by Carina Dehner, M.D., Ph.D.

Sclerosis of dermal collagen

Spongiotic dermatitis

Spongiosis: accumulation of fluid leading to intercellular edema in the epidermis
Acute: wet scale + extreme spongiosis (= intraepidermal vesicles) + eosinophils in the inflammatory infiltrate
Subacute: hyperkeratosis with little parakeratosis + mild acanthosis + mild spongiosis
Chronic: mild hyperkeratosis + marked acanthosis + minor spongiosis

Contributed by Carina Dehner, M.D., Ph.D.

Spongiosis

Vasculopathic / vasculitic dermatitis

Leukocytoclastic vasculitis: associated with infections, drugs, autoimmune diseases, etc.
- Granuloma faciale: form of leukocytoclastic vasculitis, Grenz zone
- Erythema elevatum diutinum
Occlusive vasculopathy: fibrin thrombi filling venules and capillaries

Contributed by Carina Dehner, M.D., Ph.D.

Fibrinoid material within vessels

Vesiculobullous dermatitis

Subcorneal split:
- Pemphigus foliaceus:
  - Intercellular IgG, C3 on direct immunofluorescence (DIF)
  - Sparing of basal layer
- Acute generalized exanthematous pustulosis (AGEP):
  - Neutrophils, eosinophils in dermal infiltrate
  - Negative DIF
Suprabasal split:
- Pemphigus vegetans:
  - Neutrophilic abscesses
  - Intercellular IgG, C3 on DIF
- Pemphigus vulgaris:
  - Eosinophils, neutrophils, tombstone appearance
  - Intercellular IgG, C3 on DIF
- Darier disease:
  - Acantholysis and dyskeratosis
  - Negative DIF
Intraepidermal split:
- Bullous arthropod bite:
  - Spongiotic edema, eosinophils
  - Negative DIF
Subepidermal split:
- Dermatitis herpetiformis:
  - Neutrophils in the dermal papillae
  - Granular IgA on DIF
- Porphyria cutanea tarda:
  - Cell poor split
  - IgG around superficial dermal vessels on DIF
- Bullous pemphigoid:
  - Eosinophil rich
  - Linear IgG and C3 at the dermoepidermal junction on DIF
- Linear IgA bullous dermatosis:
  - Neutrophil rich
  - Linear IgA at the dermoepidermal junction on DIF

Contributed by Carina Dehner, M.D., Ph.D.

Subcorneal acantholysis

Acantholytic blister with tombstone

Additional references

J Allergy Clin Immunol 2020;145:1031, Elston: Dermatopathology - Expert Consult, 3rd Edition, 2018

Board review style question #1

What is a Majocchi granuloma?

Deeper fungal infection in which fungi surround degenerate hair shafts
Necrotizing granuloma seen in infectious diseases, such as tuberculosis
Nonnecrotizing granuloma seen in diseases such as sarcoidosis
Palisaded histiocytic granulomatous process with central fibrin, seen in rheumatoid nodule
Palisaded histiocytic granulomatous process with central mucin, seen in granuloma annulare

Board review style answer #1

A. Majocchi granuloma is a deep fungal infection involving hair follicles caused by dermatophytes, such as T. rubrum

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