Relationship between sonographic and pathologic findings in epidermal inclusion cysts

Abstract

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.

Epidermal Cysts in the Superficial Soft Tissue

“…1-3,10,11 A congenital epidermal cyst may be formed by trapping of displaced embryonic epithelial rests, commonly occurring in the head and neck. 2,3,10 An acquired epidermal cyst results from occlusion of the pilosebaceous unit or implantation of viable epidermal cells in the dermis or subcutis. 2,5,14 Epidermal cysts are usually solitary, but multiple epidermal cysts can occur in patients with Gardner syndrome, particularly on the face and scalp.…”

“…2 An epidermal cyst frequently remains asymptomatic unless complicated by rupture or infection. 3,10 Malignant transformation into low-grade squamous cell carcinoma was reported in 72 of 3300 epidermal cysts. 1,15 In this study, none of our patients had a definite relevant surgical or trauma history accounting for formation of the epidermal cyst.…”

“…[5][6][7][8][9] By virtue of the superb capability of sonography for depicting the details of superficial lesions, epidermal cysts may appear as hypoechoic to hyperechoic masses or complex lesions depending on the composition of the cyst. 3,10,11 Of note, scrotal epidermal cysts, which appear as welldefined ovoid masses with homogeneous low to medium echoes on sonography, mimicking polyorchidism, have been described. 12,13 However, extrapolation of this sonographic pattern, the so-called pseudotestis pattern, for diagnosing epidermal cysts in the superficial soft tissue has not been advocated.…”

Epidermal inclusion cyst crystals

“…Due to the MRI features of isointense T1 and hyperintense T2 of the EIC, the lesion was thought to contain liquid material. On ultrasound, EIC has previously been described as a well-defined hypoechoic mass containing variable internal echoes in the subcutaneous layer, with posterior acoustic enhancement and lack of Doppler signal (5). Despite the lack of anechoic ultrasound appearance, bursitis or complex ganglion cyst was suspected as opposed to EIC in the preoperative diagnosis.…”

Imaging Findings of Chest Wall Lesions on Breast Sonography

“…They can be caused by surgery, needle biopsy, or penetrating trauma but can also arise in preexisting sebaceous cysts when a squamous epithelium grows down into the fundus of the gland. [13][14][15] On sonography, epidermal inclusion cysts have been described as circumscribed hypoechoic solid-or complex-appearing masses containing variable echogenic foci without color Doppler signals (Figure 9). …”