Adenoid squamous cell carcinoma(ASCC) is an uncommon variant of squamous cell carcinoma. Some of these tumors have a more aggressive growth pattern with distant metastasis and poorer prognosis compared with squaemous cell carcinoma. ASCC occurs exclusively in sun exposed areas of the skin, especially the head and neck. ASCC originating from other areas of the skin or mucosa, such as lip, oral cavity, tongue, vulva, conjunctiva and penis have also been reported but it is extremelly rare for the tumor to originate from the breast skin
Clear cell squamous cell carcinoma is a cutaneous condition, a subtype of squamous cell carcinoma, characterized by keratinocytes that appear clear as a result of hydropic swelling.
Spindle cellsquamous cell carcinoma (SCSC) is a rare variant of SCC. Clinically, it may appear as an exophytic tumor or an ulcerated mass on the sun-exposed skin of elderly patients. Unlike conventional SCC, the tumor cells infiltrate the dermis singly, without the formation of nests and cords.There may or may not be connection to the overlying epidermis. Mitoses and bizarre pleomorphic giant cells may be frequently seen.
Basaloid squamous cell carcinoma (BSCC) is a biologically virulent neoplasm found chiefly in the head and neck region especially at the base of tongue, pyriform sinus, supraglottic region of the larynx and palatine tonsils
Signet-ring cell squamous cell carcinoma is a cutaneous condition, a subtype of squamous cell carcinoma, characterized by concentric rings composed of keratin and large vacuoles corresponding to markedly dilated endoplasmic reticulum
Verrucous carcinoma is an uncommon variant of squamous cell carcinoma. This form of cancer is often seen in those who chew tobacco or use snuff orally, so much so that it is sometimes referred to as “Snuff dipper’s cancer.” It is also known as an Ackerman tumor. Most patients with verrucous carcinoma have a good prognosis. Local recurrence is not uncommon, but metastasis to distant parts of the body is rare. Patients with oral verrucous carcinoma may be at greater risk of a second oral squamous cell carcinoma, for which the prognosis is worse.
Keratoacanthoma(KA) is a relatively common low-grade malignancy that originates in the pilosebaceous glands and closely resembles squamous cell carcinoma (SCC). The pathologist often labels KA as “well- differentiated squamous cell carcinoma, keratoacanthoma variant”. KA is characterized by rapid growth over a few weeks to months, followed by spontaneous resolution over 4–6 months in most cases. keratoacanthoma A reportedly progresses, although rarely, to invasive or metastatic carcinoma; therefore, aggressive surgical treatment often is advocated.