title: Infundibular (follicular) and infundibulocystic squamous cell carcinoma: a clinicopathological and immunohistochemical study.
abstract: Two types of squamous cell carcinoma (SCC), which are considered to show infundibular differentiation, have been described so far; namely, follicular SCC and infundibulocystic SCC. The latter includes (1) a well-differentiated form, (2) a less-differentiated form, and (3) an infiltrative variant. This study examined the clinicopathological features of 8 cases of SCC with infundibular differentiation, which included follicular SCCs and infundibulocystic SCCs (a less-differentiated form and an infiltrative variant). The present study confirmed that these SCCs with follicular differentiation are clinicopathologically distinct from keratoacanthoma. However, one example of infundibulocystic SCC (less-differentiated form) proved to be difficult to distinguish from keratoacanthoma. The relationship between the follicular SCC and the less-differentiated form of infundibulocystic SCC was investigated. At the periphery of the latter lesions, a focus corresponding to the follicular SCC or advanced follicular SCC lesions was seen. Therefore, these 2 types of SCCs are considered to be similar and thus represent the same neoplastic disease. The less-differentiated form of infundibulocystic SCC is considered to be a more aggressive condition. A unified term, infundibular (follicular) SCC, was used to describe these 2 conditions in this study. The clinicopathological features of the infiltrative variant of infundibulocystic SCCs were unique and distinct from the other 2 types of SCCs. This variant of infundibulocystic SCC is therefore considered to be a distinct entity and therefore has been simply called infundibulocystic SCC in this study. Infundibulocystic SCC may therefore be related to either a microcystic adnexal carcinoma or a malignant counterpart of the trichoadenoma of Nikolowski.
authors.affiliation: Division of Dermatology, Department of Internal Medicine, Saga University, Saga, Japan. misago@post.saga-med.ac.jp
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Misago
authors.forename: Takuya
authors.initials: T
authors.lastname: Inoue
authors.forename: Shuji
authors.initials: S
authors.lastname: Toda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Narisawa
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*