Ultrasonographic features of fibrous hamartoma of infancy

Objective: To review imaging features of fibrous hamartoma of infancy (FHI), focusing on ultrasonography (US) findings. Materials and methods: We retrospectively reviewed pediatric patients who were diagnosed with pathologically confirmed FHI in two children's hospitals from 2004 to 2013. Imaging features of US, Doppler US, and magnetic resonance imaging (MRI) were evaluated. Results: Thirteen pediatric patients (M:F = 7:6; age 5-22 months, mean 11.3 months) were included. Mean lesion size was 3.2 cm (range, 0.7-8.0 cm). The tumors were located in the back (n = 4), scrotum (n = 2), scalp, shoulder, axilla, forearm, intergluteal cleft, inguinal area, and thigh. US was performed in 11 patients. With the exception of two scrotal masses, all masses were located in the dermal and subcutaneous layer. All masses demonstrated heterogeneous hyperechogenicity with a "serpentine pattern" of intervening hypoechoic portions in the hyperechoic mass. The margins were ill-defined (n = 9) or lobulated (n = 2). Doppler US was performed in nine patients and showed no (n = 6) or minimal (n = 3) vascularity. MRI was performed in five patients and the masses showed heterogeneous signal intensity with the presence of fat on T1- and T2-weighted images. Conclusions: FHI is a tumor that is typically located in the dermal and subcutaneous layer in young children less than 2 years old and presents as a heterogeneously hyperechoic mass with a "serpentine pattern" and ill-defined or lobulated margin on US and no remarkable vascularity on Doppler US.