Epithelioma of Malherbe: new ultrasound patterns

Abstract

BackroundCalcifying epithelioma of Malherbe, or Pilomatricoma, is considered an uncommon cutaneous neoplasia, normally occurring in children as a solitary, firm, asymptomatic, hard, subcutaneous, slowly growing nodule on the face, neck, or proximal upper extremity. In literature, two Pilomatricoma ultrasound patterns are described: the totally calcified nodule and the hypoechoic nodule with internal calcific foci. High frequency ultrasound has not yet been applied for routine diagnosis of Pilomatricoma. The aim of the study was to retrospectively identify specific ultrasound features.MethodsWe retrieved 124 histologically Pilomatricoma cases: 28 patients with 32 lesions were preoperatively evaluated with ultrasound.Results22/32 have shown a solid formation, hypoechoic, with a sharp outline. Of these 22, 10 lesions were completely calcifying and 12 partially calcified. In 3/32 lesions with uncertain diagnosis, ultrasounds showed a complex/mixed pattern with pseudo-fluid areas and microspots. 7/32 lesions with US different diagnosis included 3 complex lesions, 2 cystic lesions and 2 solid nodular lesions.ConclusionIn addition to well-known ultrasound patterns (completely calcified and partially calcified) we identified three new, not yet described, patterns that constitute the 31% of the cases: complex, pseudocistyc and pseudotumoral.

Calcifying epithelioma of malherbe (Pilomatrixoma): Clinical and sonographic features

“…Some studies have described the US appearance of a well‐defined subcutaneous mass with strong posterior acoustic shadowing . Solivetti et al described five US patterns to differentiate pilomatrixoma from other subcutaneous tumors . Regarding the internal vascularity noted on color Doppler imaging, it is worth noting that Ichikawa et al described the angiographic findings of calcifying epithelioma as hypervascular with arterial encasement .…”

“…11 Solivetti et al described five US patterns to differentiate pilomatrixoma from other subcutaneous tumors. 13 Regarding the internal vascularity noted on color Doppler imaging, it is worth noting that Ichikawa et al described the angiographic findings of calcifying epithelioma as hypervascular with arterial encasement. 14 The differential diagnosis of calcifying epithelioma includes sebaceous cyst, hemangioma, epidermoid and dermoid cysts, and lymph node calcification.…”

Common Applications of Dermatologic Sonography

“…Hyperechoic spots that correspond to calcium deposits are detected at the center of the lesion in 68% to 80% of cases 20 , 21 . Occasionally, pilomatrixomas can show prominent vascularity with low‐velocity arterial and venous vessels (color Doppler imaging), sometimes mimicking a vascular tumor such as a hemangioma in the clinical examination 22 – 24 . In addition, there is a cystic variant of pilomatrixomas that appears as a solid‐cystic structure with an eccentric nodular hypoechoic component surrounded by anechoic fluid.…”

Cystic pilomatrixoma of the wrist mimicking a ganglion cyst in a child

“…2,4 A pilomatrixoma develops from an unusual formation of cells, similar to hair cells, that become calcified or hardened. 2,5,6 These hardened cells accumulate under the skin and appear as a bump. The tumor is composed of islands of epithelial cells made up of varying amounts of uniform basaloid cells and shadow (ghost) cells.…”

“…2 Etiologically, pilomatrixomas are thought to be due to genetic factors, with mutations in the ss-catenina gene (CTNNB1) observed in at least 76% of pilomatrixomas. 2,5 On ultrasonography, pilomatrixomas appear as well-defined, oval, hypoechoic, heterogeneous subcutaneous masses with a hypoechoic rim. They are confined to the subcutaneous fat layer.…”