Various types of tumors can affect the subungual space, including benign solid tumors (glomus tumor, subungual exostosis, soft-tissue chondroma, keratoacanthoma, hemangioma, lobular capillary hemangioma), benign cystic lesions (epidermal and mucoid cysts), and malignant tumors (squamous cell carcinoma, malignant melanoma). Imaging plays an important role in the detection and differentiation of subungual tumors because of their small size, nonspecific clinical manifestations, and functional significance. Ultrasonography (US)-in particular, high-resolution US with color Doppler studies-provides useful information regarding tumor size, location, shape, and internal characteristics (cystic, solid, or mixed), but it is limited in the further characterization of tissue. Magnetic resonance (MR) imaging has an important role in categorizing tumors according to their anatomic location, pathologic origin, and signal characteristics. There is some overlap between the US and MR imaging features of subungual tumors; however, certain features can allow accurate diagnosis and expedite management when correlated with clinical and pathologic findings.

Neoplasms and tumorlike lesions that originate from chest wall tissues are uncommon compared with tumors in other parts of the body, and unfamiliarity with these disease entities can cause diagnostic difficulties for radiologists. Furthermore, the imaging features of many of these tumors are nonspecific, particularly those that are locally aggressive. However, a systematic approach based on patient age, clinical history, lesion location, and characteristic imaging findings often helps limit the differential diagnosis. Primary chest wall tumors can be classified as bone or soft-tissue tumors, with the latter being further classified into adipocytic tumors, vascular tumors, peripheral nerve sheath tumors, cutaneous lesions, fibroblastic-myofibroblastic tumors, and so-called fibrohistiocytic tumors, largely based on the 2002 World Health Organization classification. Within each category, it is possible to further limit the differential diagnosis with cross-sectional imaging. Information on specific features (eg, mineralization, fibrosis, hemosiderin deposits) and imaging patterns (eg, the "target sign" and "fascicular sign" seen in neurogenic tumors) can aid in making the diagnosis. Radiologists can achieve a sufficiently specific diagnosis of bone tumors and soft-tissue tumors if typical findings are present.

Sonography can be a primary diagnostic technique for evaluating nasal fracture in children. It inflicts no radiation, provides various imaging planes without positional change, and can be used to evaluate the cartilaginous septum. Potential pitfalls are the nasofrontal suture, the junction between the nasal bone and the pyriform aperture of the maxilla, the vascular groove, and the presence of an old fracture. CT can be used in addition to sonography in cases of suspected complex facial bone trauma.

The malignancy rate of AUS/FLUS nodules in our study cohort was higher than previously reported. Nodules with suspicious features on ultrasound had a higher malignancy rate than did those with indeterminate features on ultrasound. The malignancy rate differed according to histologic subcategory; therefore, management of AUS/FLUS nodules should be tailored according to histologic subcategory.