Broad Classification
- Skin tumours:
- Benign
- Malignant
Benign Skin Tumours
Skin Tags:
- Description:
- Loose fibrous tissue
- dead skin
- Identification: Common, identifiable by appearance
Syringomas:
- Mnemonic: Syrincoma () → comma cells → comma () yil kidakkunna aalde kannil synringe (periorbital are) vach valich → watery fluid () vann
- Description: Benign tumour of the acrosyringium
- eccrine sweat glands
- Appearance:
- Grouped, shiny
- asymptomatic
- Location: Periorbital area
- Contents: Watery fluid
- Borders: Angular
- Histopathology:
- Tadpole or comma cells
Dermatofibroma (Benign Fibrous Histiocytoma):
- Description: Solitary lesion
- Hyperpigmented to skin colour
- Round or oval shape
- Papule, nodule, or plaque
- Key Sign: Dimple sign
- Dimpling in center when stretched
- Location: Lower legs
- Histopathology:
- Storiform, cartwheel, or whorled pattern
- Elongated spindle cells with elongated nuclei
- Radiating from central point
Malignant Skin Tumours (Skin Cancers)
- Types: Melanoma, non-melanoma
- Non-melanoma:
- BCC: No precursors
- SCC: Has precursors
Non-Melanoma Skin Cancers
Precursors of SCC (Pre-lesions):
Actinic Keratosis (AK):
- Description: Small papules
- Rough, scaly surface
- Adherent yellowish crust
- Pinpoint bleeding when crust removed
- Premalignant
- Location:
- Photoexposed parts of elderly or white populations
- Lips, forearms
- Mnemonic: Actors Bleed when exposed
Bowen's Disease (Intraepidermal or In situ SCC):
- UV light exposed
- Description: Malignant, stays in situ
- Plaque with adherent crust
- No pinpoint bleeding
- Location:
- Lower legs of elderly females
- Mnemonic: Bowen → Bowing → Ladies, Legs
Squamous Cell Carcinoma (SCC):
- Origin: Epidermal keratinocytes or appendages
- Commonality: Second most common skin tumour
- Immunocompromised:
- Commonest in these states (e.g., HIV, renal transplant)
- Spread: Low rate of spread
- Local, regional, distant
Presentation:
- Varied
- Papule, nodule, or ulcer with crusting
- Photoexposed areas
- Difficult to diagnose clinically
Histopathology:
- Keratin pearls
Keratoacanthoma (KA):
- Mnemonic:
- Akkante () Breast → well defined rounded mounted
- Akkante () Lip (epidermal lipping) suck cheyth (SCC)
- Classical Feature:
- Well-defined, round with central crater
- Large papule/nodule
- central keratinic crust/plug
- Filled with necrotic keratinic material
- Reclassification: Well-differentiated SCC with good prognosis
- Location: Face (common), hands
- Phases: Growth, maturation, resolution (resolves on its own)
- Histopathology: Epidermal lipping
- Differentiation: Not to be confused with Henderson-Patterson bodies
- molluscum contagiosum
Basal Cell Carcinoma (BCC) / Basalioma / Rodent Ulcer:
- AKA Rodent ulcer / Basalioma
Rodent ulcer
Hedgehog pathway inhibitor
Artificial (Artefact) Palaruvi (Peripheral True Palisading)
- Commonality:
- Most common human cancer
- Growth & Metastasis:
- Very slow-growing
- Very locally invasive
- Rarely metastasizes (good prognosis)
- A/w Gorlin syndrome
- Origin: Basal layer of epidermis or follicular structures
- Features:
- Locally invasive (does not metastasize)
- lymph nodes negative.
- M/c subtype is Nodular
Clinical:
- Most common site:
- Face (medial canthus)
- above line joining angle of mouth to earlobe
- Pearly nodule with
- rolled out edges, indurated margins.
- Ulcer with
- overhanging thready margins
- Telangiectasias (fine blood vessels)
- Bleeds on touch
Microscopic Features:
- Peripheral True palisading.
- Retraction artifact.
Treatment for BCC:
- Mohs micrographic surgery
- Small, low-risk, or superficial:
- Imiquimod,
- 5-Fluorouracil,
- Photodynamic Therapy (PDT),
- intralesional alpha 2B therapy
- Large or recurrent:
- Wide local excision
- Targeted:
- Vismodegib (hedgehog pathway inhibitor)
Photodynamic Therapy (PDT)
- Principle: Photosensitizer + light + oxygen → ROS → cell death.
- Uses: Cancers, precancerous lesions, dermatology.
- Advantages: Selective destruction, spares normal tissue.
Color changes:
- Lesion remain unchanged or turn red → dark brown/black → crust → falls off.
Malignant Melanoma
- Origin: Melanocytes
- Metastasis: Very common
Types:
Type | Description |
Superficial spreading | • m/c in pre-existing mole • Seen in sun exposed areas • e.g : Subungual melanoma (Hutchinson sign) |
Lentigo maligna | • In situ melanoma in elderly • Best prognosis • Insitu melanoma |
Acral melanoma | • m/c in dark skinned patients |
Nodular melanoma | • Most aggressive, rapid vertical phase of growth • Worst prognosis • Amelanotic melanoma : Variant of nodular type |
Hutchinson's
- H → Herpes Zoster Ophthalmicus
- U → subUngual Melanoma (superficial spreading melanoma)
- Hutchinson sign
- T → Triad → congenital syphillis
- Peg shaped teeth
- Interstitial Keratitis (IK + SNHL)
- SNHL
- CH → Chauffeur's Fracture/Backfire Fracture
- Intra articular #
- Son → looking older → Hutchison Gilford
- LMN A gene defect (laminopathy).
- Progeria (onset: Child)
- PUPIL → Hutchinson Pupil
- Herniation of uncus (medial temporal lobe) → compresses ipsilateral CN III → same side pupillary dilatation.
- Kernohan’s notch phenomenon:
- False localizing sign
- Ipsilateral pupil dilatation
- Ipsilateral UMN palsy
Precursor Lesions:
- Large congenital melanocytic nevi (CMN):
- Trunk, especially >20 cm with satellite lesions
- High chance of conversion
- Junctional nevi: Highest risk of transformation
- Atypical or dysplastic nevi
Investigations:
- Biopsy (Confirmatory):
- IHC markers
- S-100, Melan-A, HMB-45.
ABCDE Changes (for pre-existing mole -> malignant transformation):
- Asymmetry: Mole asymmetrical
- Borders: Irregular
- Color: Different colours
- Diameter: Larger than pencil eraser
- >6 mm.
- Evolution: Sudden changes in size, shape, colour
Staging:
- Clarke & Breslow:
- Depends on depth of invasion.
- TNM staging.
Management:
- Wide local excision.
- Margins measured before excision, based on Breslow depth
- Sentinel lymph node biopsy
Prognostic Factor:
- Lymph node status >>> Breslow thickness
- mitotic rate, ulceration
- Special Stains:
- Masson fontana
- Enzyme stain:
- Dopa oxidase.
- Immunohistochemistry:
- HMB45
- S100
- Mnemonic: Her Brain was full of Black Malam (Brain has melanin in substantia nigra) → She was dumb (Mandana → masson fontana)→ But Dope (Dopa oxidase) looking and good hump (HMB45) and base (Stratum basale)
Mycosis Fungoides (MF)
- Paul (Pautriers) tried sex (sesary) with
- mike (mycosis) → 45 yr old and
- dani (denileukin) → 4 yr old
- → Into brain (cerebriform nucleus)
- Description:
- Cutaneous T-cell lymphoma (CTCL) variant
- T-cell tumour in skin
- Cell Proliferation:
- CD4 positive &
- CD45 RO positive helper T-cells
- Course: Very indolent
- Metastasis: Very commonly seen
- Skin biopsy:
- Pautrier's microabscesses (cancer cell clusters).
- Blood spread → Sézary Syndrome.
- Sézary cells with cerebriform nuclei (brain-like).
- DNA analysis
- Clonal arrangement of T cell receptor genes (TCR gene) → Standard now
- Mycoides → Fungal → Flower like
- Fungoides → T cell cancer ⇒ Clonal arrangement of TCR
Clinical Presentation:
- Location:
- Trunk (central girdle),
- upper lower limb
- Central body
- Stages:
- Patches,
- plaques,
- tumour/nodular,
- erythroderma
Sezary Syndrome:
Triad
- Erythroderma
- Peripheral lymphadenopathy
- Sezary cells (>20% lymphocyte count OR >1000 cells/mm³)
- Atypical lymphocytes
- Grooved or cerebriform nucleus
- Seen in tissue & blood
- Mnemonic: Sezary cell → Sezary seed → middle groove (+)
- Cerebriform appearance
- Inverted papilloma → Thala (Cerebriform) thirinjavan
Histopathology:
- Epidermotropism:
- Many T-lymphocytes in epidermis
- Pautrier's microabscesses:
- Collections of T-cells forming microabscesses in epidermis
- Poultry → easily infected with fungus → fungoides
Treatment:
- Total Skin Electron Beam Therapy (treatment of choice)
Newer Drug:
- Denileukin Diftitox (IL2 fusion toxin)
- Mnemonic: Di → Di → 2
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