Subcutaneous Fat Necrosis of the Newborn: A Case Report

Subcutaneous fat necrosis in the newborn is an uncommon transient disorder of the subcutaneous adipose tissue that develops after birth. We describe the characteristic ultrasonography and CT findings of a case of pathologically confirmed subcutaneous fat necrosis located at the subcutaneous fat layer of the neck, back, and shoulders with a review of the literature.

Ruptured Epidermal Inclusion Cyst in the Axilla: A Case Report

Epidermal inclusion cysts, the most common type of simple epithelial cyst, are typically well-encapsulated, subepidermal and mobile nodules. They may occur anywhere, but are mostly found on the scalp, face, neck, trunk, and back. Less than 10% of epidermal inclusion cysts occur on the extremities, and even fewer are found on the palms, soles, and breasts. If epidermal inclusion cysts rupture, foreign body reaction, granulomatous reaction or abscess formation could follow. We described here the sonographic findings of ruptured epidermal inclusion cyst of the right axilla in a 33-year-old woman who presented with a palpable axillary mass forming an inflammatory abscess. Address for reprints : Hak Hee Kim, M.D., Department of Radiology, Asan Medial Center, University of Ulsan, College of Medicine 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea.

Radiologic Findings of Epidermal Cysts in the Trunk

PURPOSE: To evaluate the ultrasonographic (US) or computer tomography (CT) findings of surgically proven epidermal cysts in the trunk, and to compare the echogenicity of cysts with internal contents. MATERIALS AND METHODS: Forty-five patients were retrospectively evaluated. US and CT findings of epidermal cysts were assessed in regard to location, size, shape, number, echogenicity, posterior sound enhancement, internal density, septa, mural nodule and calcification, perilesional infiltration, contrast enhancement, and internal contents. RESULTS: All 45 patients (M: F=29: 16; US in 26, CT in 19) had only one cyst, and they were located in the buttocks (n=19), back (n=13), inguinal (n=4), posterior neck (n=3), perineum (n=2), abdominal wall (n=2), presternal (n=1), and axilla (n=1). Of 26 patients who underwent US, there were 8 cases of homogeneously hypoechoic mass (30.8%), 8 of inhomogeneously hypoechoic mass (30.8%), 7 of homogeneously hypoechoic mass with internal hypoechoic lines and echogenic spots (26.9%) and 3 of homogeneously hypoechoic mass with internal echogenic spots (11.5%). Posterior sound enhancement was noted in 21 patients (80.8%). Of 19 patients who underwent CT, there were 14 cases of simple cyst (73.7%) and 5 of abscess-like lesion (26.3%). Overlying skin thickening (n=13), contrast enhancement of cystic wall (n=11), perilesional infiltration (n=7), and internal septa (n=6) were demonstrated. The internal contents of the cysts were keratinous (n=27, 60.0%) or greasy (n=15, 33.3%) material. There was no statistical significance between the echogenicity of the cysts and the internal contents (p >0.2). CONCLUSION: Epidermal cysts showed homogeneous or inhomogeneous hypoechoic mass with posterior sound enhancement on US. There was no relationship between the echogenicity of the cysts and the internal contents. In the case of ruptured cyst, an abscess-like lesion with wall enhancement and perilesional infiltration was noted on CT scan.

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

Pilomatricoma is an uncommon benign skin neoplasm arising from the hair matrix. The radiologic features of this uncommon tumor have occasionally been described in the literature 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. In this article, we describe the imaging findings of a case of pilomatricoma involving the upper arm, with the emphasis being placed on the sonographic and MR imaging findings and a review of the literature.

Inflammatory Myofibroblastic Tumor of Perineal Soft Tissue: A Case Report

Inflammatory myofibroblastic tumor is a rare benign condition of unknown etiology, and it may simulate malignancy. It is composed of myofibroblast, plasma cells and histiocytes and is found in lung, the liver, orbit, skin, mesentery, retroperitoneum and maxillary sinus. We report a case of inflammatory myofibroblastic tumor of perineal subcutaneous fat in a 35-year-old woman who complained of a palpable mass. Ultrasonography revealed a well-marginated lobulated hypoechoic lesion with peripheral poorly-defined hyperechoic strands in the subcutaneous fat of the right perineum. The lesion demonstrated low signal intensity on T1-weighted images and of heterogenous high signal intensity on T2-weighted images, compared with surrounding muscle. After intravenous injection of gadolinium, it showed clear homogeneous enhancement but poorlydefined adjacent strands. The final histologic diagnosis was inflammatory myofibroblastic tumor.

Ultrasonographic and MR Findings of Cysticercosis in Soft Tissue: A Case Report

We describe an unusual case of cysticercosis in soft tissue. On US, a well-defined oval shaped cystic lesionwith an inner central hyperechoic portion was noted. This portion showed high signal intensity on T1-weightedimages and equivocal enhancement. On MRI, other portions of the lesion showed their cystic nature. Pathologicexamination confirmed the presence of cysticercosis and, in particular, the central portion was found to be amural nodule with scolex. Cysticercosis in the soft tissue and musculature of patients from endemic areas shouldthus be considered in the differential diagnosis of an incidental mass, especially when this is cystic and has aninner central nodule.

Usefulness of Sonography in Detection of Local Recurrent Soft Tissue Tumors

PURPOSE: To evaluate the usefulness of ultrasonography in the diagnosis of local recurrent soft tissue tumors. MATERIALS AND METHODS: We retrospectively analysed the results of 113 sonographic examinations in 102 patients (38males, 64 females) after surgical treatment of soft tissue tumors (82 malignancies, 20 benignancies) during thelast five years. Follow-up included physical and sonographic examinations using a 5-10MHz transducer every twomonths. In 17 cases, MR images were obtained The criterion for local recurrence was discrete mass, and size,shape, margin, echogenicity, and homogeneity were also analysed. Forty-one patients underwent surgery. RESULTS: Among 113 cases, 41 local recurrences were proven by surgery and histological analysis; well-defined, ovoid,homogeneous hypoechoic masses of various sizes were apparent. Sonographic sensitivity and specificity were both97%. MR sensitivity and specificity were 83% and 100% respectively, but in most cases in which MR had been usedthe masses were greater than 3cm in diameter. Two cases were false positive; these were thought to be granulomas,but were shown during follow-up lasting 36 and 14 months, respectively, to be unchanged hypoechoic nodules. Onecase was false negative. CONCLUSION: For the diagnosis of local recurrent soft tissue tumors, ultrasonography isvery useful. For early detcction, it is superior to MR imaging.