Differential diagnosis in the pediatric population and in this anatomical location can be done with cranial/nodular fasciitis, low-grade fibromyxosarcoma
, low-grade myofibroblastic sarcoma, lipofibromatosis, malignant peripheral nerve sheath tumor, myofibroma, leiomyosarcoma, inflammatory myofibroblastic tumor, and hypertrophic scar [13, 27].
FNAC of low grade fibromyxosarcoma
yielded myxoid material and smears showed moderate cellularity of loosely cohesive spindled fibroblast-like cells with moderate atypia arranged in a myxoid background.
Less common types of STS occurring in the external ear included sarcoma (NOS), spindle cell carcinoma, giant cell carcinoma, epithelioid sarcoma, fibrosarcoma (NOS), fibromyxosarcoma
, pigmented dermatofibrosarcoma, liposarcoma (NOS), myxoid liposarcoma, epithelioid leiomyosarcoma, embryonal rhabdomyosarcoma, mixed tumor malignant, and carcinosarcoma (NOS).
IMT is distinguished from myxofibrosarcoma and low-grade fibromyxosarcoma
by the presence of diffuse inflammation and absence of typical delicate "curvilinear" vessels characteristic of these sarcomas.