Multiple Giant Pilar Cyst Distributed Over the Body Since Childhood.

Trichilemmal cyst or pilar cyst is defined as a cyst containing keratin and its breakdown products. It is usually situated on the scalp with a wall resembling external hair root sheath. In this case report we present a 55-year-old man with multiple giant pilar cysts that were distributed over the whole body since childhood. One of the cyst on the chest was transformed to squamous cell carcinoma (SCC).

What was known?

Pilar cysts are common, and benign lesions and malignant transformation in them is extremely rare.

Background

Trichilemmal cyst or pilar cyst is defined as a cyst containing keratin and its breakdown products. It is usually situated on the scalp with a wall resembling external hair root sheath. This is quite a common condition and women are affected more frequently than men. It is seen mainly in the at middle age and is inherited in an autosomal dominant fashion.[1] In this case report, we present a 55-year-old man with multiple giant pilar cysts that were present since childhood. One of the cyst on the chest was transformed to squamous cell carcinoma (SCC).

Case Report

A 55-year-old man was referred to us because of multiple cystic lesions located on the body, some of them measuring several centimeters [Figures 1–6]. Most of the lesions were located on the left side of the body. The family history of patient was negative for similar lesions. These lesions were present since childhood, and during this period the patient had no complaint except cosmetic concerns. Patient had ignored these lesions for many years until one of the lesions on the chest became ulcerated and then infected [Figure 5]. We excised five of the lesions on different parts of the body. We also performed biopsy from the lesion of the chest. Pathology of the lesion located on the chest showed neoplastic proliferation of the epithelial cells. These cells had vesicular nuclei with prominent nucleolus along with eosinophilic cytoplasm. Atypia along with mild pleomorphism and mitosis was also observed [Figure 7]. The squamous nests and keratin pearl was also observed in some sections. Pathology of the five other lesions showed a cystic lesion covered with stratified squamous epithelium without granular layer containing homogenous laminated keratin. This pathology confirmed the diagnosis of pilar or trichilemmal cyst [Figure 8]. Mohs surgery was performed to excise large SCC of the chest, and the site of operation was repaired by split-thickness skin graft technique. The patient visited every month for 1 year and during this period he showed no sign of recurrence in the operation site. Also, no change was observed in the remaining pilar cyst of the patient and he is now followed every 6 months.

Figure 1

Multiple pilar cysts were located on the body, extremities and head. One of the lesions on the chest was transformed to SCC

Figure 6

Pilar cyst of the scalp

Figure 5

A close view of the SCC showing large infected ulcer

Figure 7

Pathology of the lesion on the chest showing squamous nests in well-differentiated SCC

Figure 8

Pathology of pilar cyst showing trichilemmal pattern of keratinization (×400)

A closer view of the Figure 1

Close up of lesions on the trunk

Pilar lesions on the back of patient

Discussion

Pilar cysts are common, occurring in 5-10% of population. They are the second most common keratinizing cyst on the scalp. They are benign lesions and malignant transformation in them is extremely rare. Inheritance may occur in an autosomal dominant pattern. Pilar or trichilemmal cysts contain keratin and its breakdown products, lined by a wall resembling the external (outer) hair root sheath. Most pilar cysts occur on the scalp.[2] Our presented case has several interesting features. The patient had these lesions since childhood, although most patients with this lesions are affected in middle age.[3] The patient had negative family history for the same lesions. Although pilar cyst are usually observed on the scalp, the giant cystic lesions of our lesions were scattered over the whole body.[4] One of these lesions on the chest was transformed to squamous cell carcinoma that was excised using Mohs surgery. According to our literature review, up to now, there is no report regarding malignant transformation of the pilar cyst.

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.

What is new?

Pilar cysts may rarely transform to SCC and also may occur on many parts of the body.