0422 - Common Tumours of the Skin Flashcards
What are the layers of the skin? What structures occur in each?
Epidermis - Epithelium and Langerhans Cells
Dermis - Multiple structures incl sweat, sebaceous glands, CT
Hypodermis/Subcutis - Fat and vessels
What are the layers of the epidermis?
Stratum corneum -
(Stratum lucidum) -
S. Granulosum
S. Spinosum - multiple intercellular bridges (squamous)
S. Basale - Looks blue due to replenishing epidermal cells (high NC ratio).
(basement membrane)
(Dermis)
What are the cell types of the epidermis?
Mostly keratinocytes, with some basal cells, melanocytes, and Langerhans cells. Tumours can differentiate to each of these cells.
What are the two types of flat discoloured skin lesions?
Macule - up to 10mm
Patch - >10mm
What are the three types of raised lesions?
Papule - less than 10mm
Nodule - dome topped greater than 10mm
Plaque - flat-topped greater than 10mm
What are the three types of fluid-filled lesions?
Vesicle - less than 10mm
Bulla - greater than 10mm
Pustule - pus filled.
What are the two characteristics of invasive malignancy?
Cytological changes (hyperchromatic nuclei, high NC ratio, mitoses etc) AND Architectural changes.
What are the four major tumours of keratinocytes?
Epidermal cyst
Actinic keratosis
Squamous cell carcinoma
Keratoacanthoma
What is an Epidermal (sebaceous) cyst
Benign cyst in the dermis, lined by squamous epithelium, filled with oily keratin debris.
NOT to do with sebaceous glands.
Epithelium gets trapped in dermis, builds from that.
Treated by surgery.
What is Actinic Keratosis
Dysplastic lesion of epidermis.
Common in elderly from sun-exposed skin. Hyperkeratosis on the surface - flat.
Precursor to SCC. Known as SCC-in-situ.
What is Squamous Cell Carcinoma of the skin?
Malignant, caused by sun damages.
Nodular (raised), scaly, ulcerated.
Islands of malignant squamous epithelium invading dermis. Contain keratin pearls.
What is Keratocanthoma?
Benign, rapidly-developing nodule with keratin-filled crater ‘crateriform’.
No atypical cells, but architecture is abnormal. Self-resolving.
What is seborrhoeic keratosis?
Benign, raised warty lesion, in elderly.
Proliferation of benign basal cells.
Thickened, blue-like (basiloid) epidermis with lots of keratin pearls within lesion
Basal Cell Carcinoma
Most common skin-cancer in Aust. Rarely metastasise but very locally aggressive.
Classic appearance is ‘pearly nodule’ with telangiectasia.
Histologically - basiloid (blue) with peripheral palisading and apoptotic debris due to high turnover. Clefting around the islands post-formalin.
What is the normal appearance of a melanocyte?
Small, dark nuclei, with white cytoplasm.
Basal, sparse. May be surrounded by keratinocytes containing melanin pigment, but not pigmented themselves.
What is Ephelis (freckle)
Benign collections of melanocytes. Small, pigmented macules.
Histologically - no increase in melanocytes, but increase in melanin pigment.
Lentigo
Large, pigmented macule.
Linear melanocytic hyperplasia above the basement membrane.
What are the three types of naevi?
Junctional - melanocytes only in epidermis
Compound - Melanocytes in epidermis and dermis
Intradermal - Melanocytes in dermis
What is Melanoma
Malignant tumour of melanocytes.
Histologically asymmetrical, with architectural and cytological atypia.
Melanocytes do not shrink or stop mitosing with depth.
What are the 4 clinical types of melanoma?
Superficial spreading - sites with sporadic high sun exposure. Seen in younger people.
Nodular - appears as rapidly growing nodule, invades straight down instead of out first.
Lentigo Maligna - appears on chronically sun-exposed skin - grows out before down.
Acral/subungal - Acral or skin under nail. Can appear in non-caucasians - not related to sun exposure.
