Keratoacanthomahttps://en.wikipedia.org/wiki/Keratoacanthoma
Keratoacanthoma is a common rapidly-growing skin tumour, but unlikely to metastasize or invade. The tumor can resemble squamous cell carcinoma in shape. Keratoacanthoma is commonly found on sun-exposed skin, often face, forearms and hands.

Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. While some pathologists classify keratoacanthoma as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthoma do progress to invasive and aggressive squamous cell cancers.

○ Diagnosis and Treatment
#Dermoscopy
#Skin biopsy
  • Typical Keratoacanthoma
  • This case has a similar appearance to a wart.
References An Updated Review of the Therapeutic Management of Keratoacanthomas 36588786 
NIH
Keratoacanthoma (KA) is a common cutaneous tumor characterized by rapid growth and possible spontaneous regression. It most commonly affects older, fair-skinned males with significantly sun damaged skin. Although surgical removal with excision or Mohs micrographic surgery remains the standard of therapy, there are many alternative therapeutic modalities that can be utilized.
 A Clinical, Histopathological and Immunohistochemical Approach to the Bewildering Diagnosis of Keratoacanthoma 25191656 
NIH
Keratoacanthoma (KA) is a comparatively common low-grade tumor that initiates in the pilo-sebaceous glands and pathologically mimics squamous cell carcinoma (SCC). Essentially, strong debates confirm classifying keratoacanthoma as a variant of invasive SCC. The clinical behavior of KA is hardly predictable and the differential diagnosis of keratoacanthoma and other conditions with keratoacanthoma-like pseudocarcinomatous epithelial hyperplasia is challenging, both clinically and histopathologically.
 Intralesional Treatments for Invasive Cutaneous Squamous Cell Carcinoma 38201585 
NIH
Cutaneous squamous cell carcinoma (cSCC) is the second most frequent cancer in humans, and it is especially common in fragile, elderly people. Surgery is the standard treatment for cSCC but intralesional treatments can be an alternative in those patients who are either not candidates or refuse to undergo surgery. Classic intralesional treatments, including methotrexate or 5-fluorouracil, have been implemented, but there is now a landscape of active research to incorporate intralesional immunotherapy and oncolytic virotherapy into the scene, which might change the way we deal with cSCC in the future. In this review, we focus on intralesional treatments for cSCC (including keratoacanthoma), from classic to very novel strategies.