AN INTERESTING CASE OF FOOT DROP

Abstract

Purpose of Study – The unusual presentation of this case posed a diagnostic dilemma between a chronic haematoma and soft tissue sarcoma even after full investigation and biopsy. Salient points to differentiate between the two are discussed along with literature review.

Case Report – A 61 year old gentleman presented with sudden increase in size of an already existing swelling over the mid third of right leg associated with throbbing pain & foot drop of 4 months duration. There was no recent history of trauma or bleeding abnormalities but there was a vague history of injury to his leg during his late teens. Clinical signs showed features suggestive of malignancy with engorged veins and diffuse margins with complete foot drop (Fig 1 & 2). X-rays showed calcifications within the substance of the swelling along with proximal tibiofibular synostosis (Fig 3). MRI scan revealed a well encapsulated mass between the peroneal muscles mechanically compressing the common peroneal nerve (Fig 4). Trucut biopsy showed cholesterol clefts and areas of dystrophic calcification characteristic of chronic haematoma (Fig 5). Patient successfully underwent enucleation of the swelling along with cutaneofascial suture to obliterate the dead space leading to complete recovery of foot drop. Biopsy confirmed a Chronic Haematoma.

Discussion – Reid et al first used the term chronic expanding haematoma for haematomas that persisted and increased in size more than a month after the initiating haemorrhage. The cause of initial haemorrhage is most commonly trauma which results in displacement of skin and subcutaneous fatty tissue from more deeply located fixed fascia with formation of blood filled cysts surrounded by dense fibrous tissue. Factors in the blood-clotting cascade are said to be associated with an inflammatory reaction leading to additional bleeding from fragile capillaries and thus to additional inflammation, hence setting up a self-perpetuating process.

Although the MRI & biopsy results in this case were reassuring, the clinical scenario of sudden foot drop with increase in pain point more towards a malignant process rather than a benign condition. Some salient points to differentiate the two include that sarcoma have no history of trauma and the duration of symptoms is longer in haematoma than sarcoma. Also, sarcomas usually involve deeper structures while haematoma occur in superficial layers. It should also be noted that several soft tissue sarcoma themselves commonly reveal haemorrhagic or cystic changes. Other differential diagnosis includes myositis ossificans and tumoral calcinosis.

Conclusion – It is difficult to differentiate between chronic haematoma and soft tissue sarcoma based on clinical findings alone. X-ray and biochemical tests are always essential to rule out any fracture or bony mass but MRI is the gold standard and biopsy is the only way to rule out a malignant tumour. Surgical excision of the swelling including the fibrous pseudocapsule along with cutaneofascial suture to obliterate the dead space is the treatment of choice for chronic haematoma because aspiration of the fluid or incomplete excision could lead to recurrence, continued growth or a chronic draining sinus with or without infection.