Spectrum of intracranial and spinal epidermoids including unusual locations and imaging findings: A pictorial review

Sequestered, Iatrogenic Epidermoid Implantation Cysts Associated With Retroauricular (Wilde's) Incision

OBJECTIVE

To report two patients with iatrogenic, epidermoid implantation cysts associated with the standard retroauricular (Wilde's) incision, to establish their etiology, to explore means to prevent them, and to ensure that this experience adds to the learning curve of the surgical training of the residents.

METHODS

Case series with the review of literature.

RESULTS

One of the two patients, who had an unremarkable follow-up period after cortical mastoidectomy and cartilage tympanoplasty performed three years back, presented with a retroauricular cystic swelling visible since two months. It was hyperintense on T2-weighted magnetic resonance imaging. A sequestered cystic mass was encountered at surgery in the subcutaneous plane in association with the retroauricular scar tissue from previous surgery. In the other patient, two similar cysts (one of them sequestered) were incidental findings at revision tympanomastoid surgery. Histopathology in both instances was consistent with epidermoid cyst. Given their subcuticular location and intimate association with a pre-existing surgical scar, they were considered to be of implantation in origin. This was a potential outcome of persistent inversion of one or both skin edges following simple interrupted suturing. The reason could be a faulty surgical technique, due to improper placement of the needle with respect to skin, inadequate or uneven tissue bite, a tight knot, or failure to manually evert the apposing edges at the point(s) of suspicion.

CONCLUSIONS

Sequestered epidermoid implantation cysts due to persistent inversion of sutured skin edges are unusual complications. The illustrations in this case series emphasize the need to adhere to the basic principles of surgical practice. They provide a caveat to the resident surgeons and the faculties who supervise them, that inadvertent and apparently innocuous misses, even at the elementary steps of surgery (like suturing), could lead to complications that are unwanted and potentially avoidable.