Dermatopathology Ddx - MD Heromdhero.com/dermatopathology-ddx-morphology.pdf · The corni˚ed layer is unaltered, attesting to the acute nature of the process, and there is only a

See skin neoplasms section for mass, atypia, mitosis ddxSee nevus section for nevi ddx

Normal pigmentation

Fontana-Masson stain shows normal pigmentation at the basal cell layer.

Normal

Periodic acid–Schi� stain shows the presence of fungal hyphae within the corni�ed layer.

Dermatophytosis

Hyperkeratosis

SCC

hyperkeratosis, hypergranulosis, irregular epidermal hyperplasia, and a bandlike, predominantly lymphocytic in�ltrate that obscures the dermoepidermal junction. Melanophages are present in the dermal in�ltrate.

Lichen planus

Sebo

rrhe

ic K

erat

osis

parakeratotic burrow containing body parts of the mite of scabies. The dermal in�ammatory cell in�ltrate typically contains frequent eosinophils.

Scabies

neutrophilic aggregates underneath the corni�ed layer. Acantholytic keratinocytes may be seen in addition to neutrophils.

Subcorneal pustular dermatosis

Hyperkeratosis, hyperplasia, pseudohorn cyst

Seborrheic keratosis

Pityriasis rubra pilaris

Alternating layers of hyperkeratosis and parakeratosis in both vertical and horizontal patterns, psoriasiform epidermal hyperplasia, and mild super�cial perivascular in�ammation are seen.

high-power view shows alternating hyperkeratosis and parakeratosis with a normal granular layer.

Pityriasis rubra pilarisA

ctin

ic k

erat

osis

Verr

uca

Vulg

arisParakeratosis

focal parakeratosis with neutrophils and mild super�cial perivascular in�ammation

Dermatophytosis

Parakeratosis containing collections of neutrophils, vacuolar alteration of the basal cell layer, and patchy lichenoid and perivascular lymphocytic in�ammation are seen. Scattered necrotic keratinocytes and extravasated red cells are present.

Pityriasis lichenoides acuta

Histologic section shows parakeratosis with neutrophils, epidermal hyperplasiaand a dense bandlike in�ammatory cell in�ltrate that obscures the dermoepidermal junction

Secondary syphilis

sharply demarcated epidermal proliferation composed of keratinocytes with pale cytoplasm. Parakeratosis and neutrophils in the parakeratosis and among the clear cells are typical �ndings.

Clear cell acanthoma

papillomatous, parakeratosis, Hypergranulosispresence of koilocytes (vacuolated keratinocytes)dilated blood vessels in the papillary dermis are additional �ndings.

Verruca vulgaris

parakeratosis, hypogranulosis that spares the openings of the adnexal structuresBudding of the basal cells, keratinocytic atypia, and solar elastosis are present.

Actinic keratosis

exoendophytic neoplasm, central cup-shaped cratersurrounded by proliferation of large keratinocytes with abundant glassy cytoplasm and minimal cytologic atypia di�erentiates this form of squamous cell carcinoma from the conventional squamous cell carcinoma. Neutrophilic microabscesses may be seen at the base of the neoplasm.

Keratoacanthoma

con�uent parakeratosis and increased thickness of epidermis. The epidermis contains atypical keratinocytes with pleomorphic nuclei, dyskeratotic cells, and frequent mitotic �gures above the basal cell layer. The changes are con�ned to the epidermis, and therefore this lesion is considered a form of squamous cell carcinoma in situ.

Bowen disease

The epidermal proliferation shows tunnel-like invaginations �lled with parakeratosis.The neoplasm in�ltrates as bulbous expansions of the rete.

Verrucous carcinoma

Stratum cornea

Fontana-Masson stain shows loss of pigmentation at the basal cell layer

Vitiligo

thickening of the basement membrane

Cutaneous lupus erythematosus

granular positivity along the basement membrane of the epidermis and the adnexal epithelium. Positive �uorescence may be seen with immunoglobulin G (IgG) or IgM and C3


Intraepidermal spongiosis and collections of eosinophils both within the epidermis and in the dermal in�ammatory cell in�ltrate are seen.

Incontinentia pigmenti

Eosinophil

abundant eosinophils within the spongiotic vesicle, which favors a diagnosis of contact dermatitis.

contact dermatitis.

hyperkeratosis with follicular plugging, atrophy of the epidermis, marked vacuolar alteration of the basal cell layer, and a thickened and smudged basement membrane. Perifollicular lymphocytic in�ltrate is present.


Vacuolar alteration of the basal cell layer, epidermal atrophy, and a mild perivascular in�ammatory cell in�ltrate are seen.

Dermatomyositis

Epidermal atrophy

Acid-fast bacillus stain demonstrates the presence of acid-fast bacilli within the cytoplasm of some of the histiocytes.

Leprosy

Full-thickness epidermal necrosis with separation at the dermoepidermal junction is seen. The corni�ed layer is unaltered, attesting to the acute nature of the process, and there is only a minimal in�ammatory cell in�ltrate.

Toxic epidermal necrolysis

intraepidermal vesicle with prominent suprabasal acantholysis.

Pemphigus

Separations

subepidermal blister containing eosinophils and some neutrophils.

Bullous pemphigoid

separation at the dermoepidermal junction associated with aggregates of neutrophils, especially at the tips of the dermal papillae (papillary microabscesses).

Dermatitis herpetiformis SCC

Con�uent parakeratosis with collections of neutrophils, diminished granular layer, regular (psoriasiform) epidermal hyperplasia with thinning of suprapapillary plates, dilated blood vessels in the papillary dermis, and mild super�cial perivascular in�ammation are seen.

Psoriasis

Hyperplasia

Poro

ma

(Looks like hyperplasia)


Secondary syphilis

epidermal hyperplasia associated with suppurative and granulomatous in�ammation.

Blastomycosis

Hyperkeratosis, hyperplasia, pseudohorn cyst

Seborrheic keratosis


Clear cell acanthoma


Bowen disease

papillomatous epidermal hyperplasia associated with prominent sebaceous lobules and poorly formed follicular units.

Nevus sebaceus

Vacuolar alteration of the basal cell layer is seen, above which there are necrotic keratinocytes.

Erythema multiforme

Basal vacuole

Vacuolar alteration of the basal cell layer is seen with scattered necrotic keratinocytes within the epidermis. Lymphocytes are present at the basal cell layer and extending into the epidermis, where they may surround the necrotic keratinocytes (satellite necrosis)

acute GVHD



Necrotic keratinocytes in the epidermis, vacuolar alteration of the basal cell layer, and patchy lichenoid in�ammatory cell in�ltrate that obscures the dermoepidermal junction are seen. Histologic changes are similar to those seen erythema multiforme.

Fixed drug eruption

Well-circumscribed proliferation of an admixture of basaloid cells and cells with abundant vacuolated cytoplasm characteristic of sebaceous di�erentiation is seen.

Sebaceous epithelioma (sebaceoma)

dermal nodule of small blue cells arranged in sheets and trabeculae.

Merkel cell carcinoma

super�cial spreading. broad proliferation of large atypical melanocytes arranged in poorly formed nests at the dermoepidermal junction and within the dermis

Malignant melanoma

Vacuole

Collections of atypical lymphoid cells are seen in the epidermis (epidermotropism, Pautrier microabscesses).

Mycosis fungoides

epidermal ulceration and a dense dermal in�ltrate of lymphoid cells

Primary cutaneous large cell lymphoma

Epidermis



RBCs

Vacuolar alteration of the basal cell layer is seen, above which there are necrotic keratinocytes.

Erythema multiforme

Necrotic keratinocytes

Vacuolar alteration of the basal cell layer is seen with scattered necrotic keratinocytes within the epidermis. Lymphocytes are present at the basal cell layer and extending into the epidermis, where they may surround the necrotic keratinocytes (satellite necrosis)

acute GVHD




Fixed drug eruption

See neoplasm section

See neoplasms section for cysts

mild super�cial perivascular mixed in�ammatory cell in�ltrate and interstitial edema.

Urticaria

dilated blood vessels in the super�cial dermis surrounded by a mild perivascular in�ltrate of cells. Without a high degree of suspicion and special stains, it might be di�cult to notice that the cells are predominantly mast cells.

Urticaria pigmentosa, macular type

Giemsa stain highlights the mast cells in the in�ltrate.

Urticaria pigmentosa, macular typeEdema

Marked epidermal spongiosis with formation of spongiotic vesicles and a super�cial perivascular mixed in�ammatory cell in�ltrate are seen.

Spongiotic dermatitis


contact dermatitis.

A super�cial and deep perivascular lymphocytic in�ltrate is associated with marked papillary dermal edema.

Polymorphous light eruption

palisade of histiocytes surrounding zones of myxoid degeneration of collagenThe granulomas are typically located in the upper dermis.

Granuloma annulareMyxoid

Palisading granulomas surrounding zones of �brinoid degeneration of collagen are present within the subcutaneous tissue.

Rheumatoid noduleFibrinoid

lymphocytes and histiocytes. The cytoplasm of the histiocytes shows characteristic ground-glass appearance.

Reticulohistiocytic granuloma

Ground glass

dense dermal in�ltrate composed of histiocytes and lymphocytes. Many of the histiocytes have foamy cytoplasm, and some are multinucleated.

Necrobiotic xanthogranuloma

Histologic section shows a disrupted follicle and neutrophilic in�ltrate

Acne vulgaris

Periodic acid–Schi� stain shows fungal forms in the hair shaft of an in�amed follicle.

Majocchi granulomaHair follicle, shaft

Sebo

rrhe

ic K

erat

osis

Roundish stu�

Syri

ngom

aM

icro

cyst

ic a

dnex

al C

A

well-circumscribed dermal proliferation of basaloid cells embedded in a cellular stroma containing keratinous cysts

Trichoepithelioma

follicular di�erentiation in the form of bulbs and papillae.

Trichoepithelioma

nests, strands, and ducts composed of monomorphous epithelial cellsthe ductal structures are lined two layers of cells, and some have elongated contours (tadpole-like).

Syringoma

See cyst sectionfocal epidermal ulceration covered by neutrophilic scale crust and a lobular proliferation of vascular spaces associated with stromal edema and in�ammatory cell in�ltrate, including neutrophils.

Pyogenic granuloma

Hem

angi

oma

Histologic section shows perivascular in�ltrate of neutrophils, neutrophilic nuclear dust, and extravasated red blood cells. Deposits of �brin are present in and around the damaged blood vessels.

Leukocytoclastic vasculitis

Vascular


Urticaria

A large blood vessel located in the subcutaneous tissue shows in�ammatory cell in�ltrate in the wall and an organizing thrombus within the lumen.

Thrombophlebitis

Histologic section shows well-formed vascular spaces in the dermis �lled with red blood cells

Hemangioma

epidermal hyperplasia, hyperkeratosis, and markedly dilated vascular spaces extending into the epidermis

Angiokeratoma

dilated blood vessels surrounded by a monomorphous population of round to oval cells.

Glomangioma

focal epidermal ulceration covered by neutrophilic scale crust and a lobular proliferation of vascular spaces associated with stromal edema and in�ammatory cell in�ltrate, including neutrophils.

Pyogenic granuloma

irregularly shaped vascular spaces lined by highly atypical endothelial cells with marked nuclear pleomorphism.

Angiosarcoma

Kapo

si

patch stage. slitlike spaces between the collagen bundles and extravasated red blood cells

Kaposi sarcoma

plaque stage. spindle cell proliferation and irregular vascular spaces

Kaposi sarcoma

Slits

irregularly shaped vascular spaces lined by highly atypical endothelial cells with marked nuclear pleomorphism.

Angiosarcoma

marked thickening of the dermis with sclerotic bands of collagen extending into the subcutaneous fat

Morphea

sclerotic collagen extending into the subcutaneous fat associated with lymphocytic in�ammation.

Morphea

nodular proliferation of �broblasts associated with irregularly thickened bundles of collagen.

KeloidCollagen

Sola

r ela

stos

is

Sola

r len

tigo

Elastin


Granuloma annulare

Palisading (dermis)


Rheumatoid nodule

Palisading (subQ)small nests of basaloid cells showing peripheral palisading.

BCC, super�cial

lymphocytes and histiocytes. The cytoplasm of the histiocytes shows characteristic ground-glass appearance.

Reticulohistiocytic granuloma


Granuloma annulare

dermal in�ltrate of predominantly histiocytes, including multinucleated histiocytes containing foamy cytoplasm and nuclei arranged at the periphery in a wreathlike pattern (Touton giant cells). Lymphocytes are present in the background

XanthogranulomaGranuloma, Giant cells

zones of granulomas alternating with those of �brosis and extending into deep dermis

Necrobiosis lipoidica

histiocytes, including multinucleated giant cells surrounding zones of collagen degeneration in the deep dermis.

Necrobiosis lipoidica

Histologic section shows noncaseating granulomas within the dermis. The granulomas are composed of histiocytes with only a sparse lymphocytic component (naked tubercles).

Sarcoidosis

may resemble those of sarcoidosis. However, some of the histiocytes contain foreign-body material.

Foreign-body granuloma

poorly formed granulomas within the dermis.Some of the histiocytes have foamy cytoplasm

Leprosy


Blastomycosis Blastomycosis

Gomori methenamine silver stain demonstrates yeast forms of blastomycosis, some of which show characteristic broad-based budding.

dense dermal in�ltrate composed of histiocytes and lymphocytes. Many of the histiocytes have foamy cytoplasm, and some are multinucleated.

Necrobiotic xanthogranuloma



dense perivascular and interstitial in�ltrate consisting predominantly of lymphocytes. A signi�cant number of the lymphocytes are large and contain enlarged hyperchromatic and irregular nuclei.

Lymphomatoid papulosis

in�ltrate contains a large number of plasma cells.

Secondary syphilis


Secondary syphilis

Plasma cell

Melanoma

hyperkeratosis, hypergranulosis, irregular epidermal hyperplasia, and a bandlike, predominantly lymphocytic in�ltrate that obscures the dermoepidermal junction. Melanophages are present in the dermal in�ltrate.

Lichen planus

hyperkeratosis with follicular plugging, atrophy of the epidermis, marked vacuolar alteration of the basal cell layer, and a thickened and smudged basement membrane. Perifollicular lymphocytic in�ltrate is present.


lymphocyte

A super�cial and deep perivascular lymphocytic in�ltrate is associated with marked papillary dermal edema.

Polymorphous light eruption


Fixed drug eruption

Psoriasiform epidermal hyperplasia and a bandlike in�ltrate of lymphoid cells within a thickened papillary dermis are seen

Mycosis fungoides



highly atypical lymphoid cells with irregular vesicular nuclei and coarse chromatin. These cells are typically positive for CD30.


focal parakeratosis with neutrophils and mild super�cial perivascular in�ammation

Dermatophytosis

Neutrophil

di�use dermal in�ltrate consisting predominantly of neutrophils and extravasated red blood cells. Intact blood vessels help in di�erentiating this from leukocytoclastic vasculitis.

Sweet syndromedense di�use dermal in�ltrate of predominantly neutrophils. Blood vessels show plump endothelial lining. The in�ltrate is generally denser than that seen in Sweet syndrome.

Pyoderma gangrenosum


Blastomycosis

Histologic section shows perivascular in�ltrate of neutrophils, neutrophilic nuclear dust, and extravasated red blood cells. Deposits of �brin are present in and around the damaged blood vessels.

Leukocytoclastic vasculitis

see also sub-corneal neutrophil

separation at the dermoepidermal junction associated with aggregates of neutrophils, especially at the tips of the dermal papillae (papillary microabscesses).

Dermatitis herpetiformis

Periodic acid–Schi� stain shows fungal forms in the hair shaft of an in�amed follicle.

Majocchi granuloma

dilated blood vessels in the super�cial dermis surrounded by a mild perivascular in�ltrate of cells. Without a high degree of suspicion and special stains, it might be di�cult to notice that the cells are predominantly mast cells.




Mast cells

dense, di�use dermal in�ltrate of mast cells

Urticaria pigmentosa

Immunohistochemical stain for mast cell tryptase highlights the mast cells.


Marked epidermal spongiosis with formation of spongiotic vesicles and a super�cial perivascular mixed in�ammatory cell in�ltrate are seen.

Spongiotic dermatitis

Mixed


UrticariaPerivascular

Eosinophil

A super�cial and deep perivascular and interstitial in�ltrate is arranged in a wedge shape

Insect bite reaction

High-power view shows the presence of frequent eosinophils within the in�ltrate.

Insect bite reaction

parakeratotic burrow containing body parts of the mite of scabies. The dermal in�ammatory cell in�ltrate typically contains frequent eosinophils.

Scabies

Histiocyte

plasma cells and histiocytes. Within the cytoplasm of the histiocytes, there are organisms that are 2 to 4 µm in size. A Giemsa stain will highlight the organisms.

Leishmaniasis

Dermal in�ltrate of histiocytic cells with abundant cytoplasm and irregular lobulated nuclei; many of the cells extend into the overlying epidermis

Langerhans cell histiocytosis

Immunohistochemical stain for CD1a shows strong positivity of the histiocytic cells.


See granulomas

In�ltrate

Dermis

Section shows a predominantly lobular pattern of lymphocytic panniculitis with associated hyaline fat necrosis.

Lupus profundus

sclerotic collagen extending into the subcutaneous fat associated with lymphocytic in�ammation.

Morphea

predominantly septal involvement by a �brosing process

Erythema nodosum

broadening of the septa of the subcutaneous fat by �brosis and granulomatous in�ammation.

Erythema nodosum

Panniculitis

Subcutaneous fat necrosis

predominantly lobular pattern of in�ammationlobules containing areas of fat necrosis and a moderately dense mixed in�ammatory cell in�ltrate, including lymphocytes and histiocytes. Multinucleated histiocytes containing needle-shaped crystals in radial array are a characteristic �nding.

Subcutaneous fat necrosis

Des

mop

last

ic m

elan

oma

DFS

PSpindle, storiform

nodular stage. solid proliferation of spindle-shaped cells associated with extravasated red cells. Nuclear atypia and mitotic �gures are present.

Kaposi sarcoma

arrector pili muscle type. Fascicles of smooth muscle cells are seen within the upper part of the dermis

Leiomyoma

vascular type. A deep, dermal, well-circumscribed nodule composed of smooth muscle cells that surround and merge with the vessels walls.

Leiomyoma

spindle-shaped cells with enlarged and hyperchromatic nuclei.Mitotic �gures are present.

Leiomyosarcoma

slender spindle-shaped cells in�ltrating and replacing the subcutaneous fat.

DFSP

deeply in�ltrative proliferation of spindle-shaped cells

DFSP

dermal proliferation of spindle-shaped cells with wavy nuclei and a loose myxoid stromaMast cells are typically present in the background

Neuro�broma

Palisaded and encapsulated neuroma. well-circumscribed nodule of spindle-shaped cells with elongated nuclei and a palisaded arrangement.

Neuro�broma


Granuloma annulare

Palisading (dermis)


Rheumatoid nodule

Palisading (subQ)small nests of basaloid cells showing peripheral palisading.

BCC, super�cial

SubQ

well-circumscribed, lobulated, and partly cystic dermal nodule

Clear cell (nodular) hidradenoma

lobules of cells with clear cytoplasm and ductal lumens lined by cells with decapitation secretions and cystic spaces �lled with eosinophilic material.

Clear cell (nodular) hidradenoma

compact, wet keratin in lumen of this cyst lined by strati�ed squamous epithelium no granular layer distinguishes (vs epidermal)

Trichilemmal cyst

cyst �lled with laminated keratin lined by strati�ed squamous epithelium WITH granular layer

Epidermal inclusion cyst

This cyst, lined by only two layers of cells, inner luminal row, outer myoepithelial cellslumen contains apocrine secretions

Hidrocystoma

thin epithelial lining covered by undulating keratin layer.

Steatocystoma

Cysts

cystic epidermal invagination into which papillary structures project

Syringocystadenoma papilliferum

In contrast to syringocystadenoma, this is a predominantly dermal nodule with cystic appearance

Hidradenoma papilliferum.

complex papillary fronds lined by columnar cells with decapitation secretions.

Hidradenoma papilliferum.

papillae are lined by two rows of cells: the luminal row is composed of columnar cells with decapitation secretions. Plasma cells are present within the stroma


cystic epidermal invagination into which papillary structures project


papillae are lined by two rows of cells: the luminal row is composed of columnar cells with decapitation secretions. Plasma cells are present within the stroma


Syri

ngom

anests, strands, and ducts composed of monomorphous epithelial cellsthe ductal structures are lined two layers of cells, and some have elongated contours (tadpole-like).

Syringoma

Syringo___

Trichilemmoma

sharply de�ned proliferation of cells with clear cytoplasm resembling the outer root sheath of hair follicle.


Trichoepithelioma


Trichoepithelioma

Trich___

Kapo

si

patch stage. slitlike spaces between the collagen bundles and extravasated red blood cells

Kaposi sarcoma

plaque stage. spindle cell proliferation and irregular vascular spaces

Kaposi sarcoma

Cleft

DFS

P

nodular stage. solid proliferation of spindle-shaped cells associated with extravasated red cells. Nuclear atypia and mitotic �gures are present.

Kaposi sarcoma

arrector pili muscle type. Fascicles of smooth muscle cells are seen within the upper part of the dermis

Leiomyoma

vascular type. A deep, dermal, well-circumscribed nodule composed of smooth muscle cells that surround and merge with the vessels walls.

Leiomyoma

spindle-shaped cells with enlarged and hyperchromatic nuclei.Mitotic �gures are present.

Leiomyosarcoma

Spindle

slender spindle-shaped cells in�ltrating and replacing the subcutaneous fat.

DFSP

deeply in�ltrative proliferation of spindle-shaped cells

DFSP

dermal proliferation of spindle-shaped cells with wavy nuclei and a loose myxoid stromaMast cells are typically present in the background

Neuro�broma

Palisaded and encapsulated neuroma. well-circumscribed nodule of spindle-shaped cells with elongated nuclei and a palisaded arrangement.

Neuro�broma


Clear cell acanthoma Trichilemmoma

sharply de�ned proliferation of cells with clear cytoplasm resembling the outer root sheath of hair follicle.

Clear cells

papillomatous epidermal hyperplasia associated with prominent sebaceous lobules and poorly formed follicular units.

Nevus sebaceus

Well-circumscribed proliferation of an admixture of basaloid cells and cells with abundant vacuolated cytoplasm characteristic of sebaceous di�erentiation is seen.

Sebaceous epithelioma (sebaceoma)


Malignant melanoma

Cytokeratin stain shows perinuclear dotlike positivity of the neoplastic cells.



Mycosis fungoides



Bubbles


Bowen disease

exoendophytic neoplasm, central cup-shaped cratersurrounded by proliferation of large keratinocytes with abundant glassy cytoplasm and minimal cytologic atypia di�erentiates this form of squamous cell carcinoma from the conventional squamous cell carcinoma. Neutrophilic microabscesses may be seen at the base of the neoplasm.

Keratoacanthoma

SCCSCC

The epidermal proliferation shows tunnel-like invaginations �lled with parakeratosis.The neoplasm in�ltrates as bulbous expansions of the rete.

Verrucous carcinoma

SCC-likeBCC

Poro

ma

small nests of basaloid cells showing peripheral palisading.

BCC, super�cialnodular proliferation of basaloid cells with peripheral palisading.

BCC, nodular

irregular lobules of pleomorphic basaloid cells with scattered mature sebocytes.Mitotic �gures and individually necrotic cells are present.

Sebaceous carcinoma

BCC-like

dermal nodule of small blue cells arranged in sheets and trabeculae.


cells with scant cytoplasm and irregular nuclei. Nucleoli are inconspicuous. Mitotic �gures and individually necrotic cells are present.


Trabecula

In�ltratedilated blood vessels in the super�cial dermis surrounded by a mild perivascular in�ltrate of cells. Without a high degree of suspicion and special stains, it might be di�cult to notice that the cells are predominantly mast cells.




dense, di�use dermal in�ltrate of mast cells


Immunohistochemical stain for mast cell tryptase highlights the mast cells.


Mast cells

Dermal in�ltrate of histiocytic cells with abundant cytoplasm and irregular lobulated nuclei; many of the cells extend into the overlying epidermis


Immunohistochemical stain for CD1a shows strong positivity of the histiocytic cells.


Histiocytes

�broblasts and multinucleated histiocytes with foamy cytoplasm and hemosiderin pigment.

Dermato�broma

Psoriasiform epidermal hyperplasia and a bandlike in�ltrate of lymphoid cells within a thickened papillary dermis are seen

Mycosis fungoides


Mycosis fungoides



highly atypical lymphoid cells with irregular vesicular nuclei and coarse chromatin. These cells are typically positive for CD30.


Lymphocytes


Trichoepithelioma


Trichoepithelioma

Eccr

ine

Spir

oade

nom

a

well-circumscribed dermal nodule with occasional ductal lumina

Spiradenoma

sheets of larger cells with pale cytoplasm and smaller cells with scant cytoplasm. Globules of hyaline basement membrane–like material are present within the aggregations.

Spiradenoma

well-circumscribed dermal nodule composed of epithelial islands that are separated by thick hyaline sheaths and �t together like pieces of a puzzle

Cylindroma

Blobs

Der

mat

o�br

oma

Neu

ro�b

rom

a

well-de�ned dermal nodule of �broblasts and histiocytes.

Dermato�broma

�broblasts and multinucleated histiocytes with foamy cytoplasm and hemosiderin pigment.

Dermato�broma

Collagen

sharply demarcated intraepidermal proliferation of monomorphous cuboidal cells with scattered ductal lumina. The stroma is richly vascular.

PoromaMarked epidermal spongiosis with formation of spongiotic vesicles and a super�cial perivascular mixed in�ammatory cell in�ltrate are seen.

Spongiotic dermatitis (looks cystic)


contact dermatitis (looks cystic)

deeply in�ltrative neoplasm composed of ductal structures and keratin-�lled cysts

Microcystic adnexal carcinoma

monomorphous epithelial islands in�ltrating between the skeletal muscle �bers.


Microcystic


Trichoepithelioma

sheets of larger cells with pale cytoplasm and smaller cells with scant cytoplasm. Globules of hyaline basement membrane–like material are present within the aggregations.

SpiradenomaFollicular Sy

ring

oma

Mic

rocy

stic

adn

exal

CA

nests, strands, and ducts composed of monomorphous epithelial cellsthe ductal structures are lined two layers of cells, and some have elongated contours (tadpole-like).

Syringoma

deeply in�ltrative neoplasm composed of ductal structures and keratin-�lled cysts


monomorphous epithelial islands in�ltrating between the skeletal muscle �bers.


Round structure

Neoplasmsand Cysts

See nevus section for melanocytic ddxSee vascular section for vascular ddx

Com

poun

d ne

vus

broad proliferation of monomorphous melanocytes arranged as nests extending deep into the dermis, where they surround the adnexal structures.

Congenital melanocytic nevus

Section shows nests of monomorphous melanocytes at the dermoepidermal junctionand within the dermis, where they show maturation with progressive descent

Acquired (compound) melanocytic nevus

Clark dysplastic type. Section shows junctional nests of melanocytes with bridging between the adjacent rete and associated concentric and lamellar �broplasia. The melanocytes are slightly large and contain melanin-laden cytoplasm. The dermal nests are surrounded by in�ammatory cell in�ltrate and melanophages

Compound nevus

Nests

Spit

z ne

vus

Hyperkeratosis and parakeratosis, epidermal hyperplasia, and a proliferation of spindle and epithelioid melanocytes are seen at the dermoepidermal junction and within the dermis. Clefts around the nests and eosinophilic globules are characteristic �ndings

Spitz nevusCleft

Section shows nests of melanocytes at the dermoepidermal junction and within the dermis, where they are surrounded by a dense in�ltrate of lymphocytes

Halo nevusLymphocytes

Lent

igo

sim

plex

Linear

Blue

nev

us

deep dermal proliferation of spindle-shaped melanocytes containing abundant melanin.

Blue nevusDeep

Intr

ader

mal

nev

usIn

trad

erm

al n

evus

Dys

plas

tic

nevu

s

Mel

anom

a


Malignant melanoma

super�cial spreading. pagetoid melanocytes in a pagetoid pattern involving all levels of epidermis

Malignant melanoma nodular. Low-power view shows nodular proliferation of atypical melanocytes arranged as con�uent nests and sheets

Malignant melanoma, nodular

nodular. markedly atypical melanocytes with pleomorphic nuclei and prominent nucleoli. Mitotic �gures are present.

Malignant melanoma

Melanoma

Melanocytic

MDHero

The Practice of Surgical Pathology by MolaviDi�erential Diagnosis in Surgical Pathology by GattusoReferences:

Dermatopathology Ddx by Morphology

Documents

Dermatopathology Ddx - MD Heromdhero.com/dermatopathology-ddx-morphology.pdf · The corni˚ed layer is unaltered, attesting to the acute nature of the process, and there is only a