Tumor of the Follicular Infundibulum

Background

These tumors typically present as a solitary flesh colored lesion on the head and neck of middle-aged to elderly men and women. They are benign. Multiple tumors may occasionally occur.

OUTLINE

Epidemiology

Disease Associations

Pathogenesis

Laboratory/Radiologic/Other Diagnostic Testing

Gross Appearance and Clinical Variants

Histopathological Features and Variants

Special Stains/Immunohistochemistry/Electron Microscopy

Differential Diagnosis

Prognosis

Treatment

Commonly Used Terms

Internet Links

EPIDEMIOLOGY CHARACTERIZATION

SYNONYMS Mehregan tumor

HISTOLOGICAL TYPES CHARACTERIZATION

General
J Am Acad Dermatol 1995; 33: 979.

A superficial epithelial plate-like growth with multiple thin epidermal connections comprised of monomorphic cells with abundant cytoplasm.

VARIANTS

SEBACEOUS DIFFERENTIATION

Tumor of the follicular infundibulum with sebaceous differentiation

Meera Mahalingam, etal.

Journal of Cutaneous Pathology 2001;28 (6):314-317

Background: Tumor of the follicular infundibulum (TFI) is a relatively rare tumor which clinically presents as a solitary keratotic papule usually on the head and neck which on microscopic examination typically reveals a plate-like fenestrated epithelial tumor composed of pale staining cells.

Methods: We describe a new variant of TFI. An 80-year-old male with a history of multiple basal cell carcinomas and a squamous cell carcinoma presented with a 2-year history of a red, scaly, slightly elevated plaque on the lateral aspect of his right buttock.

Results: Histopathological examination revealed plate-like reticulate epithelial outgrowths of large and pale cells with foci of sebaceous differentiation and numerous colloid bodies. Differential diagnosis included superficial basal cell carcinoma with sebaceous and ductal differentiation, tumor of the follicular infundibulum, an unusual fibroepithelioma of Pinkus or an eccrine fibroadenoma with sebaceous differentiation.

Conclusion: This case illustrates a hybrid adnexal tumor with histologic features common to both tumor of the follicular infundibulum and superficial epithelioma with sebaceous differentiation.

TRICHILEMMAL TUMOR

Coexistence of tumor of the follicular infundibulum with an unusual trichilemmal tumor.

Inaloz HS, Inaloz SS, Unal B, Eralp A.

Am J Dermatopathol 2002 Oct;24(5):406-8 Abstract quote
Tumor of the follicular infundibulum (TFI) is a rare epithelial tumor, and its histogenesis is still somewhat debatable. The diagnosis of TFI cannot currently be made before biopsy, and it is most often misdiagnosed as basal cell carcinoma (BCC). A 78-year-old woman presented to the dermatology clinic with a slightly erythematous nodule surrounded by fine telangiectasia on her right temple.

Histopathologic examination of the lesion revealed an epithelial tumor with a plate-like growth pattern as is typical of TFI. In the same specimen, an unusual trichilemmal tumor with multiple epidermal connections was observed adjacent to the foci of TFI. The lobular tumor was composed of a large mass of keratinocytes with pale cytoplasm arranged as sheets and interconnecting ribbons. Several cells with hyperchromatic nuclei and small foci of compact cornification were also noted within the bulk of the tumor.

The histopathologic features of the unusual tumor were reminiscent of BCC with trichilemmal differentiation or desmoplastic trichilemmoma.

Weedon D. Weedon's Skin Pathology. Churchill Livingstone. 1997.

Commonly Used Terms

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Last Updated 10/15/2002

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Mehregan tumor

HISTOLOGICAL TYPES	CHARACTERIZATION
General	J Am Acad Dermatol 1995; 33: 979. A superficial epithelial plate-like growth with multiple thin epidermal connections comprised of monomorphic cells with abundant cytoplasm.
VARIANTS
SEBACEOUS DIFFERENTIATION
Tumor of the follicular infundibulum with sebaceous differentiation Meera Mahalingam, etal.	Journal of Cutaneous Pathology 2001;28 (6):314-317 Background: Tumor of the follicular infundibulum (TFI) is a relatively rare tumor which clinically presents as a solitary keratotic papule usually on the head and neck which on microscopic examination typically reveals a plate-like fenestrated epithelial tumor composed of pale staining cells. Methods: We describe a new variant of TFI. An 80-year-old male with a history of multiple basal cell carcinomas and a squamous cell carcinoma presented with a 2-year history of a red, scaly, slightly elevated plaque on the lateral aspect of his right buttock. Results: Histopathological examination revealed plate-like reticulate epithelial outgrowths of large and pale cells with foci of sebaceous differentiation and numerous colloid bodies. Differential diagnosis included superficial basal cell carcinoma with sebaceous and ductal differentiation, tumor of the follicular infundibulum, an unusual fibroepithelioma of Pinkus or an eccrine fibroadenoma with sebaceous differentiation. Conclusion: This case illustrates a hybrid adnexal tumor with histologic features common to both tumor of the follicular infundibulum and superficial epithelioma with sebaceous differentiation.
TRICHILEMMAL TUMOR
Coexistence of tumor of the follicular infundibulum with an unusual trichilemmal tumor. Inaloz HS, Inaloz SS, Unal B, Eralp A.	Am J Dermatopathol 2002 Oct;24(5):406-8 Abstract quote Tumor of the follicular infundibulum (TFI) is a rare epithelial tumor, and its histogenesis is still somewhat debatable. The diagnosis of TFI cannot currently be made before biopsy, and it is most often misdiagnosed as basal cell carcinoma (BCC). A 78-year-old woman presented to the dermatology clinic with a slightly erythematous nodule surrounded by fine telangiectasia on her right temple. Histopathologic examination of the lesion revealed an epithelial tumor with a plate-like growth pattern as is typical of TFI. In the same specimen, an unusual trichilemmal tumor with multiple epidermal connections was observed adjacent to the foci of TFI. The lobular tumor was composed of a large mass of keratinocytes with pale cytoplasm arranged as sheets and interconnecting ribbons. Several cells with hyperchromatic nuclei and small foci of compact cornification were also noted within the bulk of the tumor. The histopathologic features of the unusual tumor were reminiscent of BCC with trichilemmal differentiation or desmoplastic trichilemmoma.