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Year : 2015  |  Volume : 7  |  Issue : 4  |  Page : 179-181  

An unusual location of a pilar sheath acanthoma

Department of Dermatology, Chinese PLA General Hospital and Medical School of Chinse PLA (301 Hospital), Haidian, Beijing 100853, China

Date of Web Publication11-Dec-2015

Correspondence Address:
Chengxin Li
Department of Dermatology, Chinese PLA General Hospital and Medical School of Chinse PLA (301 Hospital), 28 Fuxing Street, Haidian, Beijing - 100853
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-7753.171586

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Pilar sheath acanthoma is a rare, benign follicular hamartoma. Mehregan and Brownstein fist reported this solitary, asymptomatic, and skin-colored nodule with a central pore-like opening in 1978. The classic location for these lesions is the upper lip of elderly patients. Here we report an interesting case of a pilar sheath acanthoma presenting on the left eyebrow in a middle-aged female. To our knowledge, this is the first reported case of a pilar sheath acanthoma in such a unique location.

Keywords: Benign follicular hamartoma, eyebrow, pilar sheath acanthoma

How to cite this article:
Ba W, Wang W, Li C. An unusual location of a pilar sheath acanthoma. Int J Trichol 2015;7:179-81

How to cite this URL:
Ba W, Wang W, Li C. An unusual location of a pilar sheath acanthoma. Int J Trichol [serial online] 2015 [cited 2023 Feb 6];7:179-81. Available from: https://www.ijtrichology.com/text.asp?2015/7/4/179/171586

   Introduction Top

Pilar sheath acanthoma is an uncommon, benign skin neoplasm not associated with other disorders. This lesion was first described by Mehregan and Brownstein. [1] The classic location for this tumor is the upper lip. A few cases have been described at other locations such as lower lip and cheeks. [2] However, there is no report of the tumor located on the eyebrows. Here, we present a case of a pilar sheath acanthoma found in such a unique location.

   Case report Top

A 52-year-old female presented with a solitary, asymptomatic nodule in the left eyebrow region for 5 years. She denied any previous trauma to the area or any previous treatment. On clinical examination, a skin-colored nodule measuring 1 cm in diameter was seen in the left eyebrow [Figure 1]. Under the clinical impression of epidermoid cyst or dilated pore, an excision biopsy was performed and sent for routinely fixed in formalin, and hematoxylin and eosin staining. At scanning magnification, a central branching cystic cavity with ketatin was seen in the center of the lesion. The cavity was lined with numerous well-defined lobulated tumor masses that radiated from the wall of the central cystic cavity into the deep dermis [Figure 2]. The cyst wall was composed of stratified squamous epithelium, including the granular layer, consistent with a pilar sheath acanthoma [Figure 3]. The lobulated tumor masses were also an epidermoid keratinization type accompanied by keratohyaline granules [Figure 4]. No organized fibrovascular stroma was seen around the tumor. Mistosis and pleomorphism were also absent. The clinical and histopathological characters suggested the diagnosis of pilar sheath acanthoma. The biopsy was also curative, and no further treatment was required.
Figure 1: A skin colored nodule diameter in 1 cm in the left eyebrow

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Figure 2: The cavity was lined with numerous well defined lobulated tumor masses that radiated from the wall of the central cystic cavity into the deep dermis (×10)

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Figure 3: The cyst wall was composed of stratified squamous epithelium including the granular layer (×100)

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Figure 4: The lobulated tumor masses was also a epidermoid keratinization type (×400)

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   Discussion Top

The pilar sheath acanthoma usually presents as a rare, benign follicular hamartoma commonly affecting middle-aged and elderly individuals. [2],[3] Clinically, a solitary, asymptomatic, skin-colored nodule, with a central pore-like opening plugged with keratin was seen. However, in our case, there is no obvious opening on the surface of the nodule. The tumor usually presents on the upper lip. [1],[2] There have been case reports which documented lesions in other locations, such as the postauricular area, [3] nasolabial fold, [4] cheek, [5] and forehead. [6] Our case is the first documented case of a pilar sheath acanthoma located on the eyebrow.

This lesion shares some characteristics with dilated pore and trichofolliculoma and, therefore, should be differentiated from these tumors. Microscopically, a dilated pore contains larger cystic spaces lined by acanthotic epithelium radiating thin strands or finger-like projections of epithelium into the surrounding connective tissue. This is different from the thicker, more lobular arrangement found in a pilar sheath acanthoma. The pilar sheath acanthoma also needs to be distinguished from trichofolliculoma, which has small hair follicles radiate from the wall of the central cystic structure. These small hair follicles are well differentiated compared to pilar sheath acanthoma. In addition, there is well-formed stroma in trichofolliculoma, which is absent in pilar sheath acanthoma. [7] In this case, abortive hair follicle-like structure is present but do not show a high degree of differentiation, hair shafts are also absent within the central cavity. These histologic findings are all consistent with pilar sheath acanthoma.

Since this lesion is benign neoplasm, they do not necessitate further treatment once the diagnosis has been determined. If the patient opts to remove these lesions, surgical excision is the first choice.

   Conclusion Top

We report a pilar sheath acanthoma beyond the classically described locations.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Mehregan AH, Brownstein MH. Pilar sheath acanthoma. Arch Dermatol 1978;114:1495-7.  Back to cited text no. 1
Ackerman AB, Viragh PA, Chongchitant N, editors. Pilar sheath acanthoma. In: Neoplasn with Follicular Differentiation. Philadelphia: Lea and Febiger; 1993. p. 509-32.  Back to cited text no. 2
Bavikar RR, Gaopande V, Deshmukh SD. Postauricular pilar sheath acanthoma. Int J Trichology 2011;3:39-40.  Back to cited text no. 3
Vakilzadeh F. Pilar sheath acanthoma. Hautarzt 1987;38:40-2.  Back to cited text no. 4
Choi YS, Park SH, Bang D. Pilar sheath acanthoma - Report of a case with review of the literature. Yonsei Med J 1989;30:392-5.  Back to cited text no. 5
Smolle J, Kerl H. Pilar sheath acanthoma - A benign follicular hamartoma. Dermatologica 1983;167:335-8.  Back to cited text no. 6
Elston DM, Ferringer T. Pilar and sebaceous neoplasms. Dermatopathology. 2 nd ed., Ch. 4. Philadelphia, PA: Elsevier-Saunders; 2014. p. 80.  Back to cited text no. 7


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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