Abstract Chronic soft-tissue haematomas are infrequently reported in the literature. We present a case of a slowly expanding post-traumatic chronic soft-tissue haematoma located anterior to the knee and leg, occurring in a region previously unreported. Both clinically and radiologically, it was impossible to distinguish the haematoma from an aggressive soft-tissue neoplasm. We review the literature and discuss the diagnostic problems related to this un- common presentation. Keywords Chronic haematoma · Soft-tissue neoplasm Introduction Chronic expanding soft-tissue haematoma should be dif- ferentiated from soft-tissue neoplasms such as sarcomas. This fine differentiation can be very difficult both clini- cally and radiologically. Various imaging modalities have been tried, and each of them shows particular characteris- tic features that are associated with chronic haematoma. In our case none of the modalities could affirmatively di- agnose the case. Eventually, we had to resort to a histo- pathological diagnosis. Case report A 70-year-old female patient with a history of non-insulin-depen- dent diabetic mellitus presented with a massive swelling anterior to her right knee and leg of 6 weeks’ duration. It had developed 2 weeks after a minor fall and had gradually increased in size. There was some associated discomfort, and the swelling was so large that it caused difficulty in walking. There was no history of a bleeding diathesis, anticoagulant treatment or similar episodes. Physical examination revealed a solitary swelling measuring 25×15 cm anterior to the right knee and extending onto the upper front half of the leg. There were no signs of inflammation or scars, and the consistency of the swelling varied from soft to firm. Fluc- tuation was variable, and transillumination was negative. It was not pulsatile, and examination of the knee was otherwise normal. Diagnostic MRI and bone scans were performed. The MRI scan (sagittal STIR, sagittal T1, coronal T2 and axial PD fat sat se- quences) demonstrated a sizeable soft-tissue mass located anterior to the patella (Fig. 1), and the appearances were thought to be con- sistent with haematoma. The knee joint itself was intact, although M. Sreenivas · A. Nihal · D. F. Ettles Chronic haematoma or soft-tissue neoplasm? A diagnostic dilemma Arch Orthop Trauma Surg (2004) 124 : 495–497 DOI 10.1007/s00402-004-0698-x Received: 19 December 2003 / Published online: 10 July 2004 CASE REPORT M. Sreenivas (✉) Centre for Magnetic Resonance Investigations, Hull Royal Infirmary, HU3 2JZ Hull, East Yorkshire, UK Tel.: +44-1482-674091, Fax: +44-1482-320317, e-mail: aprilsreenivas@hotmail.com A. Nihal Department of Orthopaedics and Trauma, Hull Royal Infirmary, HU3 2JZ Hull, East Yorkshire, UK D. F. Ettles Department of Radiology, Hull Royal Infirmary, HU3 2JZ Hull, East Yorkshire, UK © Springer-Verlag 2004 Fig. 1 Sagittal T1-weighted MRI scan demonstrating a large ho- mogenous haematoma in front of the knee and leg