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Dilated Pore Of Winer (Black Head)

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Last Update: June 4, 2019.


A dilated pore of Winer (DP), first described by Louis H. Winer in 1954, is a commonly occurring benign adnexal tumor of follicular differentiation.  Although most commonly located on the head and neck, a dilated pore of Winer can also be found on the trunk of middle-aged and elderly individuals.  These clinically present as an asymptomatic, solitary, enlarged pore with a keratin plug and normal surrounding skin.  Prognosis is excellent for these lesions as they are benign and do not require any further testing or work-up.  Histopathologic evaluation can confirm the diagnosis in uncertain cases.  Removal can be performed via excision for cosmetic purposes.


Some have considered the dilated pore of Winer to simply be an epidermal inclusion cyst with reactive hyperplasia of its epithelial lining and others proposed it to be a variant of nevus comedonicus (NC).[1],[2]  However, this lesion has been shown to be a distinct entity as an adnexal neoplasm of the follicular infundibulum.[3][4]  The exact cause and pathophysiology of a DP are unknown.  Winer, in his original article, noted an association with a history of inflammatory cystic acne and other cystic processes.[5] Actinic damage has also been attributed to the development of these lesions.


Although it occurs in both sexes, a dilated pore of Winer occurs more frequently in males compared to females and is also more frequent in whites.  Most cases occur at the age of 40 and older; however, there are reports of dilated pores occurring as early as 20 years of age.


A dilated pore of Winer is characterized histopathologically by a markedly dilated follicular infundibulum extending deeply into the dermis.  The cavity is filled with lamellar keratin material.  It is lined by epithelium that is atrophic near the ostium and acanthotic at the deeper portion of the invagination.  Radiating off of the epithelium are regularly spaced, small, finger-like epithelial projections pushing into the surrounding dermis.  These finger-like projections do not contain keratin cysts, ducts, or hair shafts.[1]

History and Physical

A dilated pore of Winer will present as a single, enlarged pore. The pore may be occluded by a keratin plug with softer, white, keratin material beneath.  They are asymptomatic, and the surrounding skin appears normal however a background of actinic damage may be noted.  Inflammation or infection along with pain and swelling can occur with manipulation.  Although they have a predilection for the head and neck, particularly the face, they can also present on the trunk, most commonly the back.  Patients are usually middle-aged or older and may report a previous history of severe acne.


A dilated pore of Winer is usually a clinical diagnosis.  Histopathologic examination is not required but can be performed if the diagnosis is uncertain or in cases where the lesion is excised for cosmetic purposes.  No other testing or work-up is needed.

Treatment / Management

No treatment is required for a dilated pore of Winer.  Removal can be performed for cosmetic concern. Excision in an elliptical fashion or by punch biopsy is usually curative.[6] Merely removing the keratin material can be done using a comedone extractor. However, keratin will gradually re-accumulate within the lesion. Destructive techniques such as electrodesiccation, electrocautery, laser surgery, dermabrasion, and cryotherapy are less effective due to the deeply situated base of the invagination.[5]  There are no effective medical treatments for these lesions.

Differential Diagnosis

A dilated pore of Winer and a typical nevus comedonicus can be easily differentiated clinically as the latter is a group of multiple keratin-filled openings.  A solitary lesion of a nevus comedonicus and a DP may only be differentiated histologically. The age of onset differs between the two lesions in that a dilated pore of Winer presents in the middle-aged to elderly while an NC presents at birth or during childhood.[2]  A Pilar sheath acanthoma closely resembles a dilated pore of Winer clinically as both have a central dilated opening filled with keratin and both commonly occur on the face of older adults.  Pilar sheath acanthomas occur most commonly on the upper cutaneous lip and have a more papular component compared to the dilated pore of Winer.  Histologically the pilar sheath acanthoma has a more proliferative wall with thicker acanthotic projections radiating from the central cavity, which may contain keratin cysts, squamous eddies, or sebaceous ducts.[1]  An epidermal inclusion cyst with a punctum may also clinically resemble a dilated pore of Winer and can also commonly occur on the face and trunk. Epidermal inclusion cysts have a more nodular component which is usually freely mobile and does not contain a keratin plug. They contain thick, cheesy, keratin material which has a foul odor when expressed.  Histologically epidermal inclusion cysts differ in that they present as a true cyst in the dermis with a lining of stratified squamous epithelium with a granular layer and filled with loose lamellar keratin.  Although rare, some basal cell carcinomas (BCC) can have an associated dilated pore. These large-pore BCCs tend to occur on the face of men and may be confused for a DP.  A large-pore BCC will have a history of slowly enlarging over years and may or may not have keratin debris.  Patients will tend to have thick sebaceous skin and have a history of tobacco use.[7]


Complete excision of the lesion is curative. Incomplete excision can result in recurrence from the remaining infundibular lining.  To date, there have been no reports of death associated with a dilated pore of Winer.  Also, there have been no reports of syndromes associated with this entity. There have been rare case reports of other malignant cutaneous neoplasms such as basal cell carcinoma and squamous cell carcinomas arising in dilated pores of Winer. However, these are most likely coincidental.[8],[9]  There has been one case report of a trichoblastoma arising in a dilated pore of Winer.[10]  Inflammation or infection of the surrounding skin can result from manipulation of the lesion by the patient in an attempt to remove the keratin plug.


Complications of surgical removal include scarring, infection, and bleeding. completely after surgery can be minimized by using proper aseptic or clean technique.  Infection prior to or following surgery can be treated using topical or oral antibiotics depending on severity.

Enhancing Healthcare Team Outcomes

A dilated pore of Winer is best managed by a multidisciplinary team that includes a dermatologist, primary care provider and nurse practitioner. Although these lesions are benign in most cases, a biopsy is required to rule out malignancy in elderly individuals. The majority of patients seek medical help for cosmesis. The prognosis for most patients is excellent.


To access free multiple choice questions on this topic, click here.

Pore of Winer


Pore of Winer. Image courtesy S Bhimji MD


Morikawa T, Takizawa H, Ohnishi T, Watanabe S. Dilated pore: a case report and an immunohistochemical study of cytokeratin expression. J. Dermatol. 2003 Jul;30(7):556-8. [PubMed: 12928547]
WINER LH. The dilated pore, a tricho-epithelioma. J. Invest. Dermatol. 1954 Sep;23(3):181-8. [PubMed: 13201810]
Tellechea O, Cardoso JC, Reis JP, Ramos L, Gameiro AR, Coutinho I, Baptista AP. Benign follicular tumors. An Bras Dermatol. 2015 Nov-Dec;90(6):780-96; quiz 797-8. [PMC free article: PMC4689065] [PubMed: 26734858]
Mittal RR, Sethi PS, Jha A. Dilated pore of Winer. Indian J Dermatol Venereol Leprol. 2002 Jul-Aug;68(4):239-40. [PubMed: 17656953]
Steffen C. Winer's dilated pore: the infundibuloma. Am J Dermatopathol. 2001 Jun;23(3):246-53. [PubMed: 11391113]
Benedetto AV, Benedetto EA, Griffin TD. Basal cell carcinoma presenting as a large pore. J. Am. Acad. Dermatol. 2002 Nov;47(5):727-32. [PubMed: 12399765]
Carlson-Sweet KL, Weigand DA, MacFarlane DF. Trichoid basal cell carcinoma found in a dilated pore on the nose. Dermatol Surg. 2000 Sep;26(9):874-6. [PubMed: 10971562]
Zhao L, Xu J, Fang F, Qian G, Wang Y, Wang QQ. Squamous cell carcinoma found in a dilated pore. J Eur Acad Dermatol Venereol. 2007 Feb;21(2):277-8. [PubMed: 17243983]
Misago N, Sada A, Narisawa Y. Trichoblastoma with a dilated pore. J. Am. Acad. Dermatol. 2006 Feb;54(2):357-8. [PubMed: 16443076]
Jakobiec FA, Bhat P, Sutula F. Winer's dilated pore of the eyelid. Ophthalmic Plast Reconstr Surg. 2009 Sep-Oct;25(5):411-3. [PubMed: 19966665]
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