A rare complication of congenital afibrinogenaemia - Bone cysts

Clinical History

13-year-old girl presented with history of pain in the left thigh for the past 25 days. No history of trauma or fever. Recent X-ray and CT reports revealed lytic lesion in the femur. Past medical history revealed that she had been diagnosed with congenital afibrinogenaemia shortly after birth because of bleeding from the umbilicus.

Imaging Findings

Cystic intramedullary lesion was noted involving the proximal and mid shaft of the left femur, measuring 18 cm in length and 1.8 cm in width. Thin internal septae with endosteal scalloping along the length of the lesion was seen. The lesion appeared hyperintense on T1WI Fat Sat and STIR sequences were consistent with blood degradation products. Intermediate signal within the lesion on T2WI and STIR sequences was noted suggestive of subacute haemorrhage. No cortical break or associated soft tissue component was seen. No periosteal reaction was noted. The muscles of the thigh showed normal signal intensity. Screening of the right thigh also showed a similar-appearing lesion and blood degradation products within. Review of recent X-ray chest coincidentally showed a lytic lesion in both humeri.

Discussion

Congenital afibrinogenaemia is a rare autosomal recessive disease which is caused by absence of fibrinogen or factor 1 that results in impaired blood coagulation. The normal value of fibrinogen in the blood is 2 to 4 g/l [1]. In congenital afibrinogenaemia the fibrinogen level is less than 0.2 g/l. There is no predisposition to any gender and males and females are equally affected. The estimated prevalence of this disorder is 1 in a million [2]. This disease is often diagnosed in the neonatal period with 85% presenting with umbilical cord bleeding [3] or bleeding into the gastrointestinal tract, genitourinary tract or into the skin or central nervous system. Musculoskeletal bleeding, including haemarthroses may also occur. Unusual manifestations of afibrinogenaemia include spontaneous rupture of the spleen and presence of bone cysts [4]. Bone cysts, which are one of the rarest complication of afibrinogenaemia, are caused by intraosseous haemorrhage, particularly at the entrance of the nutrient artery [5]. They commonly appear in the contiguity of the cortex or trabeculae in the diaphysis of long bones. Femora, tibiae and humeri are the commonest sites. MRI shows multicystic lesions with septa formation involving meta-diaphyseal junction of the long bones. Intraosseous haemorrhage is better diagnosed on MRI. Whole body MRI screening may be useful to evaluate lesions in other regions. X-ray shows lytic lucent lesions in the diaphysis of long bones. Large bone cysts may cause trabeculae remodelling which may result in pathological fractures in the weight-bearing bones. Furthermore haemorrhage occurs in the bone cysts which causes pain and may be the presenting symptom.

Differential Diagnosis List

Final Diagnosis

Bone cyst with haemorrhage, as a complication of afibrinogenaemia.

URL:	https://www.eurorad.org/case/13979
DOI:	10.1594/EURORAD/CASE.13979
ISSN:	1563-4086