Most of these cancers are squamous cell carcinomas. Mostly these are squamous cell carcinomas. Chronic cases can develop into squamous cell carcinomas. Rare subtypes include carcinoid tumors, bronchial gland carcinomas, and sarcomatoid carcinomas. Most squamous cell carcinomas are removed with surgery. Ochronosis can subsequently lead to lesions and squamous cell carcinomas. Primary ovarian squamous cell carcinomas are rare and have a poor prognosis when advanced. Squamous cell carcinomas of the skin may also occur. Most anal cancers are squamous cell carcinomas (epidermoid carcinomas), that arises near the squamocolumnar junction. G3 neoplasms are called neuroendocrine carcinomas (NECs). Histologically, TCCE resembles endometrioid carcinoma and is distinct from other transitional cell carcinomas. Promoter hypermethylation of "MLH1" occurs in 48% of non-small-cell lung cancer squamous cell carcinomas. Some particular forms of squamous cell carcinomas have a higher mortality rate. One method of classifying squamous cell carcinomas is by their appearance under microscope. In particular, HPV16 is a causal factor for some head and neck squamous-cell carcinomas (HNSCCs).