Case reports of diagnostic error: liposarcoma mistaken for hematoma in an obese female with concurrent ipsilateral thrombosis on rivaroxaban.

We report the case of a morbidly obese 49-year-old female found to have a 16×14×10 cm high grade myxoid liposarcoma of the thigh initially diagnosed as a hematoma. Recent initiation of rivaroxaban for a coincident ipsilateral popliteal vein thrombosis placed hematoma high in the differential diagnosis. Despite its large size, the mass was not directly appreciable on physical exam due to excess adjacent adipose tissue. Diagnostic success was achieved only after anchoring bias was abandoned and adaptive expertise was applied.