Giant calcifying epithelioma of Malherbe (pilomatrixoma): imaging features

Abstract

We present a case of giant calcifying epithelioma of Malherbe (pilomatrixoma) in the right upper arm of a 62-year-old man. It measured 18 x 12 x 8 cm in size, making it the largest of all the cases reported previously. CT clearly demonstrated a well-defined, subcutaneous mass with amorphous calcifications. The mass showed intermediate signal intensity on T2*-weighted MR images and slight contrast uptake on contrast-enhanced MR images. Histopathologically, this tumor showed no aggressive or malignant nature. The patient is without evidence of recurrence or metastasis 3 years following the resection.

Atypical adult non-calcified pilomatricoma

“…First, it was quite large, and to our knowledge, is one of the largest ever reported [7]. Second, the location of the tumor is atypical.…”

“…De Beuckeleer et al described MRI findings in pilomatricoma with homogeneous intermediate signal intensity on T1-weighted images and inhomogeneous intermediate signal intensity on gradient echo and T2-weighted images [1]. Finally, Ichikawa et al noted the same findings on T1-weighted and T2*-weighted images [7]. Amorphous calcification accounted for the inhomogeneous appearance.…”

A Case of Pilomatricoma in the Upper Arm: Sonographic and MR Imaging Findings

“…Clinically, the mass usually manifests as a solitary, slowgrowing, firm dermal nodule, which is often accompanied by inflammation or discoloration of the overlying skin (3). In most cases, the diameter of the tumor ranges from 0.5 to 3 cm, but a case of giant pilomatricoma with a maximum diameter as large as 18 cm has been reported (2). Most occurrences are solitary lesions, but multiple tumors occur in 2 3.5% of cases.…”

“…In these reports, the CT findings of pilomatricoma were described as well-defined subcutaneous masses adherent to the skin with various amounts of calcification (2,4,5). De Beuckeleer et al (7) reported two cases of pilomatricoma in the forearm that were of homogenous intermediate signal intensity on the SE T1-weighted images and predominantly low-to-intermediate signal intensity on the T2-weighted images.…”

“…The preoperative diagnosis of this entity may be difficult because of its multiple manifestations (1), especially if the examining physician is unfamiliar with them. There have been some reports in the radiological literature which included the CT (2,4,5) and MR (2, 6 8) imaging findings of pilomatricoma however, to the best of our knowledge, there have been no reports in Korea on the sonographic and MR imaging findings of pilomatricoma involving the upper arm. Knowledge of the imaging findings of this uncommon tumor would provide clinicians with useful information and facilitate the correct management of this condition.…”