Pathophysiology
neoplasm of keratinizing epidermal cells
Signs and Symptoms
1) presents in variable forms – ulcerated nodule, superficial erosion, or verrucous papule or plaque 2) ill-defined margins 3) can be fixed to underlying structures 4) has metastatic potential (1%-3%)
Histology/Gross Pathology
premalignant forms – 1) actinic keratoses 2) actinic cheilitis 3) Bowen’s disease
Associated Conditions
1) cumulative exposure to sunlight (especially UV-B) 2) arsenic 3) cyclic aromatic hydrocarbons in tar and soot 4) cigarette smoking and oral tobacco 5) chronic immunosuppression 6) HIV 7) burns 8) chronic ulceration/wounds 9) xeroderma pigmentosa 10) some forms of albinism
Biochemistry
1) considered an angiogenic tumor 2) inactivation of p53 tumor-suppressor gene 3) downregulation of thrombospondin-1 and upregulation of vascular endothelial growth factor
Inheritance/Epidemiology
1) 250,00 new cases in USA each year 2) increased incidence in males, older age, Celtic descent 3) usually appears on sun-exposed areas of head and neck (left side in USA and right side in UK)
Treatment
1) surgical excision 2) Mohs surgery 3) radiation 4) cryosurgery 5) if metastatic disease present – lymph node dissection, radiation, chemotherapy with cisplatin or retinoic acid and interferon 6) prevention by avoiding or blocking UV radiation
Tips for USMLE
if a 56 year old farmer has a scab on the right side of his nose for the padt 8 months that has not healed and that has gotten slightly larger in the past 3 months, think squamous cell skin cancer.
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