Monostotic fibrous dysplasia of proximal tibia: a case report

Dr Kevin Martin (SHO Emergency Medicine), Dr Housameddin Ghazzawi (Emergency Medicine Consultant), Dr Alister McIlwee (Emergency Medicine Consultant, Clinical Director Ulster Hospital SEHSCT)

The above named are the sole authors of this case.  Consent was obtained from the patient to produce this case report.

A 8-year-old boy presented to the Emergency department with a two-three month history of generalised pain and swelling around the left knee. There was no history of trauma or mechanical injury. This pain had increased in the day prior to presentation to the ED.

The patient did not have any recent foreign travel; had no night pain and the pain did not waken him from his sleep. No family history of any suspicious bone lesions. He was otherwise fit and healthy with no medical problems. He was a normal term delivery and all of his vaccinations were up to date.

On examination, there was a small effusion of the left knee associated with some generalised pain, but no specific bony tenderness. He also had some swelling of tibia anteriorly but no bony tenderness. He had a slightly reduced range of movement at the left knee.

X-rays of his knee and lower leg did not show any fracture. However they showed an incidental finding of a lesion to the proximal tibia [Figures 1 and 2]. This lesion appeared lytic in nature with some cortical involvement with the medial cortex. Given the suspicious nature of this lesion, the case was discussed with the Paediatric Orthopaedic Team. Arrangements were made for urgent outpatient follow-up by this team. Bloods were satisfactory with no systemic upset or temperatures. The patient was then discharged home from the Emergency Department. 

The patient was seen the following day by the Paediatric Orthopaedic Team where both CT [Figure 3] and MRI imaging of the lesion were carried out. This demonstrated that the lesion was a benign fibrous dysplasia.

From our literature research, this appears to be a very rare case in a patient of this age. Fibrous dysplasia lesions of the tibia are also uncommon; with only two similar case reports found (one in a 13-year-old boy and the other in a 14-year-old girl – both involving proximal epiphysis of tibia). [1,2]

Learning points:

This case highlights the importance of imaging bones above and below affected joint due to potential for referred pain. Here the patient complained of knee pain but imaging of the knee joint, thus far, has not found any abnormality and therefore it is possible that the knee pain was actually referred pain from this tibial lesion.

xray tib fib

Figure 1: Xray Tibia/fibula (anterior view) - fibrous dysplasia lesion

Figure 2: Xray tibia/fibula (lateral view)

Figure 2: Xray tibia/fibula (lateral view)

Figure 3: CT image showing fibrous dysplasia lesion of tibia

Figure 3: CT image showing fibrous dysplasia lesion of tibia

 

References:

  1. Takechi R et al. Involvement of the proximal tibial epiphysis by monostotic fibrous dysplasia. Clin Imaging 2009; 33(2): 154-7. DOI: http://dx.doi.org/10.1016/j.clinimag.2008.09.014 (Accessed 20/11/2017)
  2. Gwark J et al. Monostotic fibrous dysplasia in the proximal tibial epiphysis: a case report. Journal of Medical Case Reports 2014; 8:452. DOI: https://doi.org/10.1186/1752-1947-8-452 (Accessed 24/11/2017).

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