[Pilomatrixoma of the ocular adnexae: clinical and histologic analysis (13 cases)]

Pilomatrixoma (calcifying epithelioma of Malherbe) is a rare benign tumour originating from the matrix of the hair root. In this study, we evaluated the clinical and histopathological characteristics of all the respective tumour specimens submitted to our laboratory since 1997.

We reviewed the clinical and histologic findings of 13 pilomatrixomas localised to the ocular adnexae. Paraffin sections were stained with H&E and PAS and, in addition, immunohistochemistry was performed using markers for macrophages (CD68), for proliferative activity (Ki67), and for proliferation/apoptosis (CAS/CSE1L).

All 13 pilomatrixomas were of reddish-livid colour and localised on the upper eyelid and/or near the eyebrow. The patients ages ranged from 4 to 84 years without preference for either gender. In 3 cases the correct diagnosis was made intraoperatively, while no pilomatrixoma was diagnosed prior to surgery. The most frequent false diagnoses were retention cyst (n = 3), atheroma (n = 2), and abscess (n = 2). There was no tumour recurrence in any of the cases within the time period presented. All 13 pilomatrixomas demonstrated the characteristic histology with areas of basophilic islands, shadow cells, calcification and a chronic granulomatous inflammation with foreign body giant cells in varying amounts. Immunhistochemical staining with anti-Ki67 and anti-CAS/CSE1L indicated a regular cellular maturation of the basophilic cells. No correlation was found between any of the histological or immunohistochemical markers and clinical parameters such as size, age and gender of the patient and duration of tumour presence prior to surgery.

This case series represents one of the largest published so far, and underscores that pilomatrixoma can appear at any age. While it is usually not recognised clinically, it should be considered in the differential diagnosis especially for tumours of the upper eyelid. Our immunohistochemical findings support the basically benign nature of a pilomatrixoma but also point to the chronic inflammatory stimulus that can lead to complications after incomplete removal.