ABSTRACT
PURPOSE: This case aimed to explore the clinical, histological, and immunohistochemical features of intravascular fasciitis (IVF) that involve a large blood vessel. CASE REPORT: A 27-year-old man presented with swelling and pain of the left lower limb for 5 days. The report of Doppler ultrasonography confirmed deep venous thrombosis (DVT) in the lower left limb (acute phase). However, laboratory value for the presence of D-dimer was negative. Thus, we performed an ascending venography and identified a mass in the common femoral vein. At operation, an incision of the left common femoral vein was made, and the mass was completely resected. CONCLUSIONS: The situation of IVF that grew in a large vein is extremely rare and can easily be misdiagnosed as DVT. The presence of D-dimer is important for a differential diagnosis. Ascending venography can be applied in making an accurate diagnosis.