Epidermal inclusion cysts most often appeared sonographically as a hypoechoic mass containing variable echogenic foci without color Doppler signals. Ruptured epidermal cysts, however, may have lobulated contours and show color Doppler signals, mimicking a solid mass.

Purpose. We evaluated the sonographic findings in epidermal inclusion cysts and related them to the pathologic findings.Methods. We retrospectively reviewed the sonograms and pathology specimens of 24 patients with pathologically proven epidermal inclusion cysts. We evaluated the lesions for shape, size, internal echogenicity, posterior sound enhancement, and presence of color Doppler signals. We classified the masses into 5 sonographic types according to their internal echogenicity. The relationship between the sonographic types and the pathologic findings was examined.Results. The masses were ovoid or spherical in 17 cases (71%), lobulated in 5 (21%), and tubular in 2 (8%). The longest diameter ranged from 1 to 6 cm (mean, 3.1 cm). Twenty-three cases (96%) were associated with posterior sound enhancement. Color Doppler signals were absent in 20 cases, but some vascularity was noted in 4 ruptured epidermal cysts, in areas of granulation tissue. The most common sonographic type was a hypoechoic lesion with scattered echogenic reflectors (10 cases). Sonographic findings were related to the lamellation of keratin debris and the granulation tissue secondary to rupture.Most cases with a lobulated configuration (4 of 5) or color Doppler signals (4 of 4) were ruptured cysts.Conclusions. Epidermal inclusion cysts most often appeared sonographically as a hypoechoic mass containing variable echogenic foci without color Doppler signals. Ruptured epidermal cysts, however, may have lobulated contours and show color Doppler signals, mimicking a solid mass.

Renal hemangioma is an uncommon benign tumor which usually causes painless or painful gross hematuria. Its preoperative diagnosis is extremely difficult or even impossible.We experienced three cases of renal hemangioma, located mainly at the pelvocalyceal junction or in the inner medulla. US demonstrated variable echogenecity, and CT revealed a lack of significant enhancement. Where there is gross hematuria in a young adult, especially when the renal mass located in the pelvocalyceal junction or inner medulla shows little enhancement on CT, renal hemangioma should form part of the differential diagnosis.

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