Colossal pilomatrixoma

Abstract

We describe the largest reported case of pilomatrixoma in the literature. While pilomatrixomas typically present as small soft-tissue nodules of the head, neck and upper extremities, they can also present as much larger masses in atypical locations. When they present in their usual size, pilomatrixomas have typical imaging features and can be correctly diagnosed with imaging studies before histological confirmation. Their clinical and imaging diagnosis become challenging when they are very large, as in our case. A giant pilomatrixoma should also be considered for paediatric patients presenting with a large subcutaneous soft-tissue mass.

Giant pilomatrixoma: a distinctive clinical variant: a new case and review of the literature.

“…The most frequent location is the upper limb followed by the parotid region and the back. The size may vary and the largest lesion reported to date was 34cm in diameter [4]. Nearly 40% of the giant PMs published are ulcerated, which together with their frequent location in the parotid region, makes the initial clinical suspicion more likely to be a malignant neoplasm [1] or a parotid neoplasm [5], such as cutaneous squamous cell carcinoma, dermatofibrosarcoma protuberans, cutaneous metastases, pleomorphic adenoma, and malignant parotid tumors.…”

Pilomatrixoma Recurring as Giant Form

“…Pilomatrixoma is a benign skin tumor that originates from the hair follicle matrix [1][2][3][4][5][6][7][8][9][10]. It frequently has a bimodal distribution, with children and young adults having a higher prevalence [1,5,6].…”

“…Since its origin is located superficially, there is usually no adherence to deeper fascias, but its surface can appear reddish/bluish and even ulcerated. Size-wise, it ranges from 0.5 cm to 3 cm [1,2,5,6,8,10], but lesions with a diameter of 34 cm have been described [8]. Therefore, masses larger than 4 cm are classified as "giants" [2,5].…”

“…Other classifications include bullous, perforating/ulcerated, anetodermic, lymphangiectatic, pigmented, and familial [2,3,6,9]. Some syndromes are associated with multiple pilomatrixomas, namely Gardner syndrome, Rubinstein-Taybi syndrome, myotonic dystrophy, Kabuki syndrome, trisomy 9, Turner syndrome, and Sotos syndrome [1,3,6,8,9]. Although Turner syndrome and myotonic dystrophy represent the most frequent genetic associations with 42% of cases, no genetic anomalies have yet been established for familial pilomatrixoma [3].…”

“…Most findings are of a well-defined soft tissue mass with calcifications and no invasion of neighboring tissues. Although these are shared characteristics of other pathologies, in the preauricular area it is of utmost importance to differentiate cutaneous, vascular, and parotid tumors [2,3,5,6,8,10]. PET/CT interpretations should be very cautious, especially regarding large and deep ulcerated lesions, since both high inflammation and a high mitotic rate may increase the glucose intake and therefore reduce the diagnostic accuracy [7].…”