Soft tissue tumors seldom present as an acute problem in the emergency room. Every so often, a hemangioma thromboses or bleeds and a cystic hygroma becomes infected or encounters a bleed, but otherwise soft tissue tumors are more indolent. For the most part, soft tissue tumors are first evaluated with plain films where deep edema will be seen and then with ultrasound. Ultrasound is especially useful for the evaluation of hemagiomas and cystic hygromas along with their complications [1, 2] (Fig. 3.1).

Also somewhat rare is the acute presentation of a malignant bone tumor. Once again, these entities are somewhat indolent but every so often a patient will present because of extremity pain, and imaging will demonstrate the presence of a bone tumor, occasionally with a pathologic fracture (Fig. 3.2). In the young pediatric patient, metastatic neuroblastoma is a common entity to encounter with unexplained pain. What one see in these cases is permeated bony destruction usually around the metaphysis (Fig. 3.2c). Much more commonly, however, one will encounter a pathologic fracture in a benign lesion such as a unicameral bone cyst (Fig. 3.3).