๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
KERATOACANTHOMA
KERATOACANTHOMAย ย ICD-10: D23.L71
โข KA is a special lesion; formerly considered a pseudocancer, it is now regarded by most as a variant of SCC.
โข A relatively common, rapidly growing epithelial tumor with potential for tissue destruction and (rare) metastasis; however, in most cases there is spontaneous regression.
โข HPV-9, -16, -19, -25, -37 have been identified in KAs; other possible etiologic factors include UVR and chemical carcinogens (pitch, tar).
โข Age of onset over 40 years. Male:female ratio 2:1.
โข A dome-shaped nodule with central keratotic plug (Fig. 11-17). Firm but not hard. Skin-colored, slightly red, brown. Removal of keratotic plaque results in a crater.
โข Predilection for sun-exposed sites.
โข Multiple KAs occur.
โข Spontaneous regression in 6 to 12 months in most cases. However, local or visceral metastases have been detected.
โข Histopathology: Not always possible to rule out highly differentiated SCC.
โข Treatment is by excision.
A B
FIGURE 11-17 โข Keratoacanthoma showing different stages of evolutionโ(A) Initially there is a round domeshaped, very firm nodule, reddish with a central hyperkeratotic plug. This has been partially shed leaving a central crater. (B) Hyperkeratosis has progressed and has now replaced most of the nodule, leaving only a thin rim of tumor tissue in the periphery.