Histopath - Skin & Breast Flashcards by Rebecca Thompson

Pathophysiology of Pemphigus vulgaris

IgG binds to desmosome proteins 1,3
Intraepidermal bullae (flaccid blisters)

Histology = acantholysis, suprabasal blistering
Direct immunofluorescence = chicken wire pattern of intercellular deposits of IgG ?

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Invasive squamous cell carcinoma histology

Perineural invasion
Increased mitotic activity
Keratin ‘pearls’

Other:
Irregular aggregates of pink tumour cels
Infiltrative nests in dermis

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Basal cell carcinoma histology

Basaloid tumour
Peripheral palisading
Clefting
Mitotic activity

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Immunohistochemical stains for Malignant melanoma

Melan A
S100
HMB45

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Vesicobullous inflammatory reaction pattern

Within epidermis

Forms bullae

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Spongiotic inflammatory reaction pattern

Within epidermis

Becomes oedematous

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Psoriaform inflammatory reaction pattern

Within epidermis

Becomes thickened

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Lichenoid inflammatory reaction pattern

Within epidermis

Forms sheeny plaque?

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Vasculitic inflammatory reaction pattern

Within dermis

Associated with vasculitis

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Granulmatous inflammatory reaction pattern

Within dermis

Associated with (mainly non caseating) granuloma

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Subcutis inflammatory reaction patterns?

Panniculitis e.g. erythema nodosum

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Key histology of eczema / dermatitis

Acute = spongiotic pattern

fluid / oedema around keratinocytes
inflammatory infiltrate in dermis
dilated dermal capillaries

Chronic

acanthosis
hyper parakeratosis
T cells, eosinophils

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Key histology of Lichen Planus

Flat epidermis
Basement membrane obscured by T cells
Colloid bodies (dead looking keratinocytes)

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Koebner’s phenomenon

Psoriatic reaction at site of injury/irritation

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Mechanism of psoriasis

Abnormally rapid turnover of epidermis (6 days vs 56 days normally)

Accumulation of thick scale over sites of frequent trauma/irritation

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Key histology of psoriasis

Parakeratosis (remnants of nuclei indead keratinocytes - not time to be lost)

Hypogranulosis / Loss of stratum granulosum - no time for granular layer to form

Clubbing of rete ridges

Munro’s micro-abscesses (neutrophil recruitment) in stratum corneum

Dilated blood vessels

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Pathophysiology of Dermatitis herpetiformis

Associated with coeliac disease

IgA abs bind to basement membrane –> sub epidermal bullae

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Pathophysiology of Bullous pemphigoid

IgG binds to hemidesmosomes (of basement membrane)
Subepidermal large + tense blister (bullae)
Eosinophils - release elastase

Direct immunofluorescence: linear IgG along basement membrane
Indirect: raised serum IgG

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Pathophysiology of Pemphigus foliaceous

IgG (/ IgE?) Ab against desmoglein 1 within desmosomes
Inter-epidermal blister - not intact, appear excoriated

Histology = acantholysis, subcorneal blistering
Direct immunofluorescence = chicken wire pattern of intercellular deposits of IgG ?

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Seborrheic keratosis features

Keratin horns
Olderly proliferation
Acanthosis (thickening of epidermis)

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Clinical features of Basal cell carcinoma

Pearly lesion
Rolled edge
Central ulceration

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Cause of BCC

PTCH mutation
Usually somatic (UV exposure), rarely inherited (Gallin syndrome)

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Histology of actinic keratosis

atypia of epidermis (basal)
Abnormal stratum corneum (parakeratosis)
Basement membrane NOT lost

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Bowen’s disease (SCC in situ) histology

Pleiomorphic cells
Hyperchromatic nuclei
Disorderd maturation
Increased mitotic activity, atypical mitotic figures

Full thickness atypia BUT basement membrane intact

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Types of benign naevi (moles)

Junctional: melanocyte nests in epidermis, young people, well circumscribed, uniform pigment, flat. Compound: nests of melanocytes within epidermis + dermis, can be very large, may need multiple excisions. Intradermal: melanocytes within dermis, older patient.

Subtypes of melanoma

Lentigo maligna Superficial spreading Nodular Acral lentiginous

Histology of melanoma

Atypical melanocytes Cellular atypia in dermis Pagetoid spread of melanocytes (ascend into epidermis) Radial growth phase - horizontal in epidermis THEN vertical growth into dermis

Breslow thickness

Most important prognostic factor for melanoma Measures from granular layer --> deepest abnormal melanocyte <0.8mm = stage 1a

C1 breast cytopathology - meaning

Inadequate sample - RBC, neutrophils - Debris - Cannot see cells clearly

C2 breast cytopathology - meaning

Benign Glandular proliferation - branching, staghorn clefts - possible benign tumour

C3 breast cytopathology - meaning

Atypia, likely benign

C4 breast cytopathology - meaning

Atypia, likely malignant

C5 breast cytopathology - meaning

Malignant

Current gold standard for diagnosing breast ca.

Histopathology

Clinical features of duct ectasia

Nipple discharge breast pain mass Nipple retraction

Histology of duct ectasia

Duct distension - proteinaceous maternal inside | Foamy macrophages

Cytology of fat necrosis

Fat cells surrounded by macrophages (histiocytes)

Clinical features of acute mastitis

Painful, red breast

Cytology of acute mastitis

Acute inflammatory cells - neutrophils | Foamy macrophages

Usual causative organism of acute mastitis

Staphylococcus

Usual epithelial hyperplasia - histological features

Increased cell proliferation causing multilayering Clefts + empty spaces Contained within duct

Flat epithelial atypia / atypical ductal carcinoma - histology

Punched out margins | +/- calcification

In situ lobular neoplasia - histology

Monomorphic

Fibrocystic disease - histology

Dilated + calcified ducts

Fibroadenoma - histology

Well circumscribed | Glands compressed

Phyllodes' tumour - histology

'Leaf-like' - broad based papillae, long clefts High cellularity + Stromal overgrowth = more malignant

Intraductal papilloma - histology

Dilated ducts Polypoid mass in centre Fibrovascular core Blood vessels within stroma

Radial scar - histology

2 distinct areas: 1. central stellate scar 2. peripheral proliferation of ducts/acini

Tx of radial scar

Removal Can contain malignant cells

Tx of intraductal papilloma

Removal = curative

Tx of Phyllodes' tumour

Removal Benign, borderline + malignant types

What benign lesion can resemble ca. on imaging?

Radial scar

mobile breast lump in 28 yo woman?

Fibroadenoma

Most common ca. in women

Invasive breast carcinoma - ductal most common within this

Features of low grade Ductal carcinoma in situ

Lumens compact + regular calcification overlapping clls

Features of high grade ductal carcinoma in situ

Central lumen necrotic material | Pleiomorphic cells occlude duct

RF for invasive breast carcinoma

``` Early menarche Late menopause Increased BMI EtOH COCP +ve family Hx ```

Malignant breast cancer that does not produce mammographic densities

Invasive lobular carcinoma is picked up incidentally on biopsy

Invasive ductal carcinoma - histology

Pleimorphic cells Large nuclei, little cytoplasm E-cadherin +ve

Invasive lobular carcinoma - histology

Linear 'Indian file' pattern Monomorphic No calcification or stromal reaction?

Invasive tubular carcinoma - histology

Elongated tubules invading stroma | Associated with radial scar

Invasive mucinous carcinoma - histology

Nests of tumour cels | Extravasated mucin pools

Basal like carcinoma - histology

Sheets of atypical cells Prominent lymphocytic infiltrate Central necrosis common +ve for cytokeratins CK5/6 and 14

Nottingham grading for breast ca.

Graded histologically looking at: - tubule formation - nuclear pleomorphism - mitotic activity each scored 1-3 then totals added

Receptors checked in breast ca.

``` Oestrogen receptor (ER) Progesterone receptor (PR) Her2 status ```

Receptor status of low grade tumours

ER/PR + | HER2-

Receptor status of high grade tumours

ER/PR - | HER2+

Receptor status of basal like carcinoma

Triple negative | ER-, PR-. HER2-

Most important prognostic factor in breast ca

Axillary lymph node status