Below is an overview of the GP histopathology course. Each of the topics will have a separate illustrated post.
Here we will deal with the histopathology of the common tumours you will see in skin cancer practice. We will concentrate on those histological features that have a crucial impact in determining how you treat the lesion.
eg BCCs- Pathology relates to the treatments used
Superficial bcc V Nodular bcc V Infiltrating or Morphoeic
Thickness - penetration of creams eg Aldara and red light in PDT
Significance of Infiltrating BCC with these modalities
Basisquamous BCC
BCC with perineural spread
BCC in vessels- very rare
eg SCCs- SCC in situ- confined to epidermis
Compare and contrast clonal Seb K V SCC in situ
Invasive SCC can be well differentiated through to poorly differentiated -Significance for treatment?
SCC with perineural spread
Spindle cell tumours- Need for special stains to sort them out
Pigmented Lesions
Solar lentigo V Lentigo maligna V flat dark Seb K
Clinical V dermatoscopic V histology V Confocal microscopy
Different types of melanoma
Dysplastic nevus V Melanoma
Important clinical features- Age, other dysplastic nevi, dermatoscopic view
When to ask for further cuts
Importance of the type of biopsy used to sample the pigmented lesion.
Why partial punch biopsies are a potential death trap.
What cytological features make a melanocyte histologically atypical?
Nevi
Types of nevi- junctional, compound, dermal, congenital, dysplastic, Spitz, combined , blue
The difficulties with Spitz nevi
Pigmented non melanocytic tumours
Pigmented BCC
Pigmented SCC in situ Bowen's disease
Other Tumours- Benign and Malignant
Malignant
Merkel cell- histology, special stains, wide excision, refer, radiotherapy
AFX- Atypical fibroxanthoma, like a poorly differentiated SCC,
MFH- Malignant fibrous histiocytoma- goes deep, wide excision 10 mms.
DFX- dermtofibrosarcoma protuberans- very wide excision 3-5 cms- refer.
Recurrent SCCs- refer early, wide excision, often perineural or lymphatic spread.
Angiosarcoma- looks like a big bruise
Benign
Often face- Adnexal tumours
Eccrine glands- syringomas, hidradenomas
Hair follicles- Trichoepitheliomas, desmoplastic variant, Cylindromas
Sebaceous glands- Seb adenoma, Sebaceous carcinoma
Vascular- Pyogenic granuloma, Kaposi's sarcoma
Epidermal nevi- Sebaceous nevi- Syringocystadenoma papilliferum, Trichoblastoma, form fruste BCC
Clear cell acanthoma
LPLK
Porokeratosis
Actinic keratosis
Viral wart
