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Tumor of follicular infundibulum
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Tumor of follicular infundibulum

Contributors: Haya Raef MS, Susan Burgin MD
Other Resources UpToDate PubMed

Synopsis

Tumor of follicular infundibulum (TFI), also known as infundibuloma, is a benign cutaneous adnexal tumor. This typically presents as a solitary, smooth or keratotic papule on the head, neck, or trunk. It has also been described in case reports to occur on the extremities and vulva. Multiple TFIs is a rare clinical variant and classically presents as symmetrically distributed, hypopigmented macules or depressed papules. Multiple lesions usually range in number from 10-20. The term "eruptive infundibulomatosis" indicates hundreds of tumors. The lesions are asymptomatic but can be associated with pruritus secondary to sun exposure.

TFI usually occurs in elderly individuals. Its incidence is estimated to range between 3-20 cases per 100 000 skin biopsies. Epidemiological reports comparing rates between males and females have been inconsistent.

While the etiology of TFI is not completely understood, some describe its origin from follicular infundibulum, whereas other studies state that the name is a misnomer, as the tumor cells resemble isthmic differentiation. TFI has been described to coexist with other cutaneous lesions (both seen within the same biopsy specimen), including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), actinic keratosis, epidermal cysts, nevus sebaceus, malignant melanoma, and nevi. It is therefore also postulated that TFI lesions could represent an epidermal reactive process to the presence of the adjacent tumor.

Codes

ICD10CM:
D23.9 – Other benign neoplasm of skin, unspecified

SNOMEDCT:
254694002 – Tumor of follicular infundibulum

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Papules:
  • Seborrheic keratosis – Look for a "stuck-on" appearing verrucous papule that can range from skin-colored to brown.
  • BCC – TFI may mimic BCC clinically and is often found incidentally in the margin of excised BCC tissue. These are distinguished through histopathology. In contrast to BCC, TFI shows a dense elastic fiber network and lacks cellular atypia and expression of Ber-EP4.
  • Fibroepithelioma of Pinkus – Presents as a sharply demarcated, smooth, exophytic lesion, usually located on the lower back.
  • Trichilemmoma – Presents as a skin-colored papule that can sometimes be hyperpigmented or verrucous in appearance.
  • Actinic keratosis – Presents as a hypertrophic, rough papule with irregular borders on sun-damaged skin.
  • Trichoblastoma
Depressed papules or plaques: Hypopigmented macules:
  • Tinea versicolor – Involves a mild scale. A negative potassium hydroxide (KOH) preparation will rule out tinea versicolor.
  • Pityriasis alba – Typically affects the cheeks of atopic individuals.
  • Vitiligo – The patches are completely depigmented and very well demarcated.
  • Tuberculoid leprosy – Seen in patients living in endemic areas.
  • Idiopathic guttate hypomelanosis – Rarely involves the face. More commonly occurs on the extensor forearms and shins.

Best Tests

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Management Pearls

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Therapy

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References

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Last Reviewed:10/11/2020
Last Updated:10/11/2020
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Tumor of follicular infundibulum
Tumor of follicular infundibulum : Single skin lesion
Copyright © 2021 VisualDx®. All rights reserved.