Abstract
Epidermoid cysts are extremely common and can occur in any hair-containing area. We present the case of a 20-year-old man with an epidermoid cyst in the perianal region. Epidermal cysts have been described in this area previously after haemorrhoidectomy, but cysts of the size seen in this case are rare in the absence of previous anal trauma. The diagnosis was confirmed by excision biopsy.
Background
This case reports an unusual presentation of a common condition, which would be of educational value to the reader. In addition, it was a case we found particularly interesting as the diagnosis was challenging.
Case presentation
A concerned 20-year-old male builder presented to the outpatient clinic with a 2-month history of a painless slow-growing lump in the perianal region. There was no history of other similar lesions, or any history of previous surgery or blunt trauma to the region. The patient was otherwise fit and well and did not take any medication. On examination, there was a soft, painless 1.5-cm spherical and pedunculated lesion located at the anal margin (figure 1).
Figure 1.
Lump within the perianal region.
Differential diagnosis
The differential diagnosis of lumps, such as this found within the perianal region, include haemorrhoids and anal skin tags.
Treatment
An excision biopsy was performed and the histology of the lesion was consistent with a diagnosis of an epidermoid cyst.
Although clinical assessment and excision biopsy confirmed the diagnosis and is sufficient in most cases, imaging studies, such as ultrasonography and MRI, can be used to help characterise such lesions further.
Outcome and follow-up
Management may be conservative if the cyst is asymptomatic and surgical incision and drainage are indicated for symptomatic or infected cysts,1 or as in this case to give a diagnosis. Rare instances of cancer within cysts have also been reported.2
Discussion
Epidermoid cysts are common and can arise in any hair-containing area including the perianal region, as exemplified by this case. They typically affect young and middle-aged adults and occur due to inflammation around a pilosebaceous follicle or due to deep implantation of the epidermis by blunt or penetrating injury or surgery. Clinically epidermoid cysts are slow growing and are usually asymptomatic3; however, they can become infected or inflamed and cause pain and tenderness. Epidermal cysts have been described previously in this area after haemorrhoidectomy, but cysts of the size seen here are rare in this region in the absence of previous anal trauma.4
Learning points.
Epidermoid cysts are commonly encountered over the head and face, however can occur in any hair-containing region.
Epidermoid cysts are rarely encountered in the perianal region.
If the diagnosis of a lump is unclear, an excision biopsy should be performed or a referral made to the appropriate specialist.
Footnotes
Contributors: KS wrote the article. YG obtained consent and edited the article. HT reviewed the article.
Competing interests: None.
Patient consent: Obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.
References
- 1.Sukal SA, Myskowski PL. Safer and less unpleasant incision and drainage of epidermal inclusion cysts. Dermatol Surg 2006;32:1214–15 [DOI] [PubMed] [Google Scholar]
- 2.Morgan MB, Stevens GL, Somach S, et al. Carcinoma arising in epidermoid cyst: a case series and aetiological investigation of human papillomavirus. Br J Dermatol 2001;145:505–6 [DOI] [PubMed] [Google Scholar]
- 3.Epstein WL. Epithelial cysts in buried human skin. Arch Dermatol 1957;76:437–45 [DOI] [PubMed] [Google Scholar]
- 4.Granet E. Hemorrhoidectomy failures: causes, prevention and management. Dis Colon Rectum 1968;11:45–8 [DOI] [PubMed] [Google Scholar]