Two Cases of Pedunculated Inverted Follicular Keratosis / 대한피부과학회지

Inverted follicular keratosis is a benign, solitary skin lesion that is mainly diagnosed histologically, rather than clinically. The pathogenesis of inverted follicular keratosis has not been elucidated. It is still controversial as to whether the inverted follicular keratosis is a distinct hair follicle lesion, an old lesion of verruca vulgaris, or an irritated seborrheic keratosis. It is usually presented with a verrucous firm papule or nodular lesion clinically, and it commonly mimics other proliferative skin lesions, such as warts, cutaneous horn and basal cell carcinoma. However, inverted follicular keratosis with a pedunculated feature has been hardly found. Clinical morphology of the inverted follicular keratosismight be related with the site of tumor origin. Herein, we report two interesting cases of inverted follicular keratosis with a peculiar pedunculated feature.

Queratosis folicular invertida pigmentada: a propósito de un caso: [revisión] / Inverted follicular keratosis: a case report: [review]

La queratosis folicular invertida (QFI) es una lesión benigna del infundíbulo folicular. Es poco frecuente y habitualmente el diagnostico es histopatológico. Clínicamente no presenta características propias ni patognomónicas, por lo que generalmente semeja otras lesiones proliferativas de la piel, como las verrugas, el carcinoma basocelular, las queratosis seborreicas y otros tumores benignos. La forma pigmentada es infrecuente y suele confundirse con melanoma. La queratosis folicular invertida es una entidad de histogénesis controvertida, proponiéndose como alternativas que sea una neoplasia benigna con diferenciación folicular, una variante de verruga vulgar o una queratosis seborreica irritada. El tratamiento de la queratosis folicular invertida es la extirpación completa de la lesión, con un excelente pronóstico, casi sin recurrencias.

Inverted follicular keratosis (IFK) is a benign lesion of follicular infundibulum. It is rare, and diagnosis is usually histopathological. Clinically, it is unique, with no pathognomonic characteristics and therefore often resembles other skin proliferative lesions such as warts, basal cell carcinoma, seborrheic keratoses and other benign tumors. The pigmented form is rare and often confused with melanoma. Inverted follicular keratosis is an entity of controversial histogenesis, alternatively considered as a benign neoplasm with follicular differentiation, a variant of vulgaris warts or irritated seborrheic keratoses. Treatment for inverted follicular keratosis is the complete removal of the lesion, with excellent prognosis, almost without recurrence.

Clinical and Histopathological Features in Inverted Follicular Keratosis / 대한피부과학회지

BACKGROUND: Inverted follicular keratosis has distinctive histopathological features and is infrequently encountered by dermatologists. To date, the pathogenesis of inverted follicular keratosis has not been elucidated. Many authors have suggested several theories for the nature of inverted follicular keratosis including verruca vulgaris with squamous eddies, irritated seborrheic keratosis and distinctive follicular tumors. There are no comprehensive studies about the clinical and histopathological features of inverted follicular keratosis in Korea. OBJECTIVE: The purpose of this study was to analyze the clinical features and histopathological findings of inverted follicular keratosis with literature review. METHODS: We studied 14 patients with inverted follicular keratosis for clinical features including the duration of the disease, the location and size of the lesions, the clinical impressions at the first visit and we made a record of the patients' age and sex, histopathological findings. RESULTS: Eight of the 14 patients were male and the ages ranged from 40 to 83 years(mean 59.3 years). The lesions were situated on the face(5/14), scalp(3/14), abdomen(2/14), hand(2/14), buttocks(1/14), shin(1/14). The average size of the lesions was 1.38cm. Seborrheic keratosis was the most common clinical diagnosis(6/14), followed by verruca vulgaris(4/14), cutaneous horn(1/14), melanoma(1/14), soft fibroma(1/14) and pigmented nevus(l/14). Solid and nodular types were the most common histopathological type(7/14), followed by keratoacanthoma-like type(5/14), filiform or wart like type(2/14). CONCLUSION: Inverted follicular keratosis have unusual clinical and histopathological features. We recommend that verrucous plaque lesions should be diagnosed correctly by histopathologic examination and it may be helpful to avoid inappropriate therapeutic approach.

Clinical Features and Detection of Human Papillomavirus in Inverted Follicular Keratosis / 대한피부과학회지

BACKGROUND: Inverted follicular keratosis has distinctive histopathological features and is infre quently encountered by dermatologists. To date, the pathogenesis of inverted follicular keratosis has not, been concluded. Many authors have suggested several theories for the nature of inverted follicular keratosis including vearuca vulgaris with squamous eddies, irritated seborrheic keratosis and dist,inctive follicular tumors. OBJECTIVE: It is the purpose of this study to observe and compare the clinical features of in verted follicular keratosis with previous studies and evaluate the possible relationship between in verted follicular keratosis and human papillomavirus to clarify the nature of this condition. METHODS: We studied 9 patients with inverted follicular keratosis for clinical features including the duratiori of the disease, the location and size of the lesions, the clinical impressions at the first visit and we made a record of the patients age and sex. To evaluate the relationship be tween inverted follicular kerato is and the human papillomavirus, we performed immunohistochvm ical staining using polyclonal antibodies to the human papillomavirus common antigen. We also used the polymerase chain relation to detect hurnan papillomavirus DNA in inverted follicular keratosis from paraffin embedded tissue preparation. RESULTS: 1. Seven of the 9 patients were male and the ages ranged fiom 36 to 77 years(mean 53 years). The lesions were situat d on the face(4/9), abdomen(1/9), back(1/9), chest(1/9), scapular area(1/9) and leg(1/9). The average size of the lesions was 1.5 cm. Verruca vulgaris was the most common clinical diagnosis(3/9), followed by seborrheic keratosis(2/9), soft fibroma(2/9), pigmented nevi(1/9), and granioloma pyogenicum(1/9). 2. Immunohistochemical stainiiigs using polyclonal antibodies to the human papillomavirus common antigen were negative for all 9 cases. 3. Polymerase chain reaction; using primers for human papillomavirus DNA were negative for all 9 cases. CONCLUSION: In general, our linical findings are similar to those of others in previous studies. Our results of immunohistocheriiical staining and the polymerase chain reactions suggest, that in verted follicular keratosis is ncl, related to the human papillomavirus. Further investigations inf'o the nature of inverted follicular keratosis, should be centered on initated seborrheic keratosis and distinct follicular tumors.

A Case of Inverted Follicular Keratosis

I report a case of inverted follicular keratosis in a 68-year-old woman who presented a solitary, asymptomatic, slightly brownish verrucous nodule on her nose, present for 3 years. The lesion was characterized histologically by focal hyperkeratosis, marked acanthosis, horn cysts, numerous squamous eddies and sebaceous differentiation of the basaloid cells in the epidermis.