Pilomatricoma Mimicking Ruptured Epidermal Cyst in a Middle Aged Woman.

Pilomatricoma is a benign tumor arising from the hair matrical cells. Most pilomatricomas appear in the first two decades of life as a solitary skin to a bluish colored nodule on head-neck area with an occasional sign of inflammation. Here, we present a case of pilomatricoma which appeared at 36 years of age with a history of recurrent inflammation and discharge mimicking ruptured epidermal cyst.

What was known?

Pilomatricoma usually appears in the first two decades

Usually, an asymptomatic lesion with an occasional inflammation.

Introduction

Pilomatricoma is a common, benign skin tumor arising from the hair matrix. Most cases are associated with CTNNB1 gene mutations.[1] Usually, they present as a solitary nodule/cystic lesion distributed on head, neck, and upper trunk area. Sometimes, there is associated inflammation. The common age of occurrence is within the first two decades of life.[23]

Case Report

A 36-year-old obese, hypothyroid female patient presented in Surgery Outpatient Department of a Tertiary Care Medical College of Eastern Bihar with a bluish-red, nodular lesion over the upper back [Figure 1]. She gave a history of 6–8 months duration and complained of some sticky material coming out from the lesion intermittently whenever there was pain and redness. She was treated outside with intermittent antibiotic and anti-inflammatory agents with an apparent resolution of the symptoms followed by recurrence in a few weeks.

Figure 1

Nodule on back

On examination, we found a violaceous nodulo-cystic lesion on the upper back with a size of 2 cm × 1.5 cm; the center of the lesion was eroded, and there was a visible yellow-colored cheesy discharge from that area [Figure 2]. No puncta was visible. Depending on the site, the nodulo-cystic nature of the lesion, the recurrent history of inflammation and discharge, a provisional diagnosis of the ruptured epidermal cyst was placed. The patient was managed conservatively till discharge subsided, and the epithelialization of central area was complete. The lesion was then excised and was sent for histopathology as a routine measure.

Figure 2

Nodule covered with yellow cheesy discharge and crust

Histopathology

In scanner view, the epidermis was acanthotic. In the dermis, there was a nodular basaloid cell proliferation extending from papillary to reticular dermis [Figure 3]. There was also the proliferation of squamoid cells with the disappearance of nucleus leaving behind a shadow (ghost cells/shadow cells) [Figures 4 and 5]. The dermis was covered by mononuclear inflammatory infiltrate along with the formation of foreign body type giant cells [Figures 6 and 7]. In view of these findings, a diagnosis of pilomatricoma was reached.

Figure 3

H and E (scanner view): Basaloid cells

Figure 4

H and E (scanner view): Ghost cells

Figure 5

Ghost cells with nuclear shadow, (H and E, ×40)

Figure 6

Stromal inflammation, (H and E, ×10)

Figure 7

Foreign body giant cells, (H and E, ×40)

Discussion

Pilomatricoma is a benign tumor of hair matrix proved by immunohistochemistry and ultrastructural study. Most cases are associated with CTNNB1 gene mutations.[1] Usually, they appear in early age, the average age of onset being childhood to adolescence.[23] They usually present as a solitary firm nodule or cyst distributed on any nonglabrous area, but mostly restricted to head-neck and upper trunk. Multiple pilomatricomas may be present particularly in Gardner's syndrome.[4] Sometimes, the lesion shows an inflammatory sign. In histology,[5] usually there is a cyst formation with matrical keratinization. There are two kinds of cells; outer basaloid matrical cells and central squamatized cells with the remnant of nuclear outline (shadow or ghost cells). In the early stage, particularly, in the elderly population, the basaloid cells predominate, and these tumors are called proliferating pilomatricoma. There is a considerable granulomatous inflammation in the surrounding stroma. There may be features of calcification. The treatment is basically surgical excision; recurrence has been reported following the surgical excision.

In our case, the pilomatricoma appeared at 36 years of age, and clinically mimicked ruptured epidermal cyst. The goal of this presentation is to highlight the fact that pilomatricoma may appear late in life and matrical cyst of pilomatricoma can rupture and give rise to a clinical picture mimicking ruptured epidermal cyst.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

What was known?

Pilomatricoma appearing in the fourth decade

Presenting as a discharging nodule.