Follicular Squamous Cell Carcinoma Research Articles

Acantholytic squamous cell carcinoma is usually associated with hair follicles, not acantholytic actinic keratosis, and is not “high risk”: Diagnosis, management, and clinical outcomes in a series of 115 cases

Acantholytic squamous cell carcinoma (aSCC) is regarded as a high-risk variant of cutaneous squamous cell carcinoma (SCC). Acantholytic actinic keratosis (aAK) has been regarded as a precursor risk factor for aSCC. However, supporting evidence is limited. We sought to document clinical features, histologic features, management, and outcomes in a series of aSCC cases. Definitions of aSCC, aAK, and aSCC arising in association with aAK were applied to a consecutive series of aSCC cases. Clinical characteristics and outcomes were obtained from electronic medical records. Of 115 aSCC cases (103 patients, mean age 71.8years), actinic keratosis was present in 23% (27/115) but only 7.8% (9/115) exhibited associated aAK. Ten cases (10/115, 9%) fulfilled strict histologic criteria for follicular SCC as previously defined, but 50 of 115 (43%) of our aSCC cases exhibited predominant involvement of follicular epithelium rather than epidermis. Clinical outcome (median follow-up, 36months) was available in 106 of 115 (92%). One patient experienced regional extension (parotid), and 1 patient experienced a local recurrence (nose). No disease-related metastases or deaths were documented. This was a single-institution retrospective study from the United States. The presence of acantholysis in cutaneous SCC does not specifically confer aggressive behavior, a finding that may inform clinical practice guidelines.

Follicular cutaneous squamous cell carcinoma: an under-recognized neoplasm arising from hair appendage structures

Cutaneous squamous cell carcinoma (SCC) with no demonstrable point of epidermal origin is problematic as it raises consideration of metastatic SCC histologically. There are rare case reports and series of SCC arising from the wall of hair follicle structures. Such lesions have been termed follicular SCC (FSCC). To investigate the clinicopathological features of FSCC. We prospectively collected cases of follicular SCC over a 5-year period. Follicular SCC is defined as a cutaneous SCC deriving from a pre-existing hair follicle structure. Lesions were considered to represent 'hybrid' SCCs if an interfollicular epidermal origin was also demonstrated; SCCs with >50% of the origin from interfollicular epidermis were excluded. Histological features and clinical information were evaluated. We identified 61 cases of follicular SCC arising in 60 patients from a database of 5212 cutaneous SCCs encountered over the same time period by the same authors. There were 49 pure follicular SCCs and 12 hybrid lesions. The male to female ratio was 44:16; the mean age was 74years (range 44-93). Follicular SCC represents 1·2% of all primary SCCs. Biopsies of such lesions, if the appendage structure of origin is not represented, are histologically indistinguishable from metastatic SCC. Recognition of this under-reported form of SCC is essential if an inappropriate diagnosis of metastatic SCC, with potentially harmful and inappropriate therapy and investigation, is to be avoided.

Considerations on the Measurement of Follicular Squamous Cell Carcinoma

Considerations on the Measurement of Follicular Squamous Cell Carcinoma

Infundibular (Follicular) and Infundibulocystic Squamous Cell Carcinoma: A Clinicopathological and Immunohistochemical Study

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.

Cutaneous squamous cell carcinoma: a comprehensive clinicopathologic classification

Cutaneous squamous cell carcinoma (SCC) includes many subtypes with widely varying clinical behaviors, ranging from indolent to aggressive tumors with significant metastatic potential. However, the tendency for pathologists and clinicians alike is to refer to all squamoid neoplasms as generic SCC. No definitive, comprehensive clinicopathological system dividing cutaneous SCCs into categories based upon their aggressiveness has yet been promulgated. Therefore, we have proposed the following based upon the malignant potential of SCC variants, separating them into categories of low (< or = 2% metastatic rate), intermediate (3-10%), high (greater than 10%), and indeterminate behavior. Low-risk SCCs include SCC arising in actinic keratosis, HPV-associated SCC, tricholemmal carcinoma, and spindle cell SCC (unassociated with radiation). Intermediate-risk SCCs include adenoid (acantholytic) SCC, intraepidermal epithelioma with invasion, and lymphoepithelioma-like carcinoma of the skin. High-risk subtypes include de novo SCC, SCC arising in association with predisposing factors (radiation, burn scars, and immunosuppression), invasive Bowen's disease, adenosquamous carcinoma, and malignant proliferating pilar tumors. The indeterminate category includes signet ring cell SCC, follicular SCC, papillary SCC, SCC arising in adnexal cysts, squamoid eccrine ductal carcinoma, and clear-cell SCC. Subclassification of SCC into these risk-based categories, along with enumeration of other factors including tumor size, differentiation, depth of invasion, and perineural invasion will provide prognostically relevant information and facilitate the most optimal treatment for patients.

Cutaneous squamous cell carcinoma: a comprehensive clinicopathologic classification. Part One

Cutaneous squamous cell carcinoma (SCC) includes many subtypes with widely varying clinical behaviors, ranging from indolent to aggressive tumors with significant metastatic potential. However, the tendency for pathologists and clinicians alike is to refer to all squamoid neoplasms as generic SCC. No definitive, comprehensive clinicopathological system dividing cutaneous SCCs into categories based upon their aggressiveness has yet been promulgated. Therefore, we have proposed the following based upon the malignant potential of SCC variants, separating them into categories of low (< or = 2% metastatic rate), intermediate (3-10%), high (greater than 10%), and indeterminate behavior. Low-risk SCCs include SCC arising in actinic keratosis, HPV-associated SCC, tricholemmal carcinoma, and spindle cell SCC (unassociated with radiation). Intermediate-risk SCCs include adenoid (acantholytic) SCC, intraepidermal epithelioma with invasion, and lymphoepithelioma-like carcinoma of the skin. High-risk subtypes include de novo SCC, SCC arising in association with predisposing factors (radiation, burn scars, and immunosuppression), invasive Bowen's disease, adenosquamous carcinoma, and malignant proliferating pilar tumors. The indeterminate category includes signet ring cell SCC, follicular SCC, papillary SCC, SCC arising in adnexal cysts, squamoid eccrine ductal carcinoma, and clear-cell SCC. Subclassification of SCC into these risk-based categories, along with enumeration of other factors including tumor size, differentiation, depth of invasion, and perineural invasion will provide prognostically relevant information and facilitate the most optimal treatment for patients.

Cutaneous squamous cell carcinoma: a comprehensive clinicopathologic classification

Abstract: Cutaneous squamous cell carcinoma (SCC) includes many subtypes with widely varying clinical behaviors, ranging from indolent to aggressive tumors with significant metastatic potential. However, the tendency for pathologists and clinicians alike is to refer to all squamoid neoplasms as generic SCC. No definitive, comprehensive clinicopathological system dividing cutaneous SCCs into categories based upon their aggressiveness has yet been promulgated. Therefore, we have proposed the following based upon the malignant potential of SCC variants, separating them into categories of low (≤2% metastatic rate), intermediate (3–10%), high (greater than 10%), and indeterminate behavior. Low‐risk SCCs include SCC arising in actinic keratosis, HPV‐associated SCC, tricholemmal carcinoma, and spindle cell SCC (unassociated with radiation). Intermediate‐risk SCCs include adenoid (acantholytic) SCC, intraepidermal epithelioma with invasion, and lymphoepithelioma‐like carcinoma of the skin. High‐risk subtypes include de novo SCC, SCC arising in association with predisposing factors (radiation, burn scars, and immunosuppression), invasive Bowen's disease, adenosquamous carcinoma, and malignant proliferating pilar tumors. The indeterminate category includes signet ring cell SCC, follicular SCC, papillary SCC, SCC arising in adnexal cysts, squamoid eccrine ductal carcinoma, and clear‐cell SCC. Subclassification of SCC into these risk‐based categories, along with enumeration of other factors including tumor size, differentiation, depth of invasion, and perineural invasion will provide prognostically relevant information and facilitate the most optimal treatment for patients.

Follicular squamous cell carcinoma of the skin: a poorly recognized neoplasm arising from the wall of hair follicles.

In the last decades, a number of clinicopathologic subtypes of squamous cell carcinoma (SCC) of the skin, ranging from highly aggressive tumors with a tendency to recur and metastasize to neoplasms with a favorable prognosis, have been described. SCCs arising from the wall of hair follicles have been briefly mentioned by some authors but never reported in a series. Cases of SCC arising from the wall of hair follicles were collected from the files of two large German Centers for Dermatopathology and analyzed clinicopathologically and immunohistochemically. Sixteen cases of SCC developing in hair follicles were found among more than 7000 cases of cutaneous SCC reviewed. In most cases, tumors arose on sun-damaged skin of the face of elderly persons. There was a male predominance (11/5). The most common clinical diagnosis was basal cell carcinoma (BCC). Microscopically, tumors developed in the upper part of hair follicles without or with focal involvement of the overlying epidermis at the border with the involved follicle. Immunohistochemically, tumors were positive for cytokeratin and negative for a battery of immunomarkers, including antibodies against the most common carcinogenic human papillomaviruses (HPV) of the skin. Most tumors were excised by simple excision. In two cases, a recurrence was noted after incomplete excision. No further recurrences or metastasis have been noted after a follow-up period ranging from 11 months to 12 years. SCC of the hair follicle represents a poorly recognized but distinctive subset of SCC of the skin that should be considered in the differential diagnosis of other cutaneous epithelial tumors. The term follicular SCC (FSCC) is proposed for this neoplasm.