The diagnosis is very difficult on radiographical
The diagnosis is very difficult on radiographical imaging alone as many tumours have similar radiological appearances to desmoplastic fibroma [2,7]. Biopsy is the gold standard method of determining the exact nature of any bony lesion as it provides a tissue diagnosis. The biopsy ideally should be performed at a reference bone tumour centre under the auspices of a fully accredited multi-disciplinary team. A unit familiar with the diagnosis of such rare pathology can, therefore, evaluate the clinical, radiological and histological features of this difficult disease so as to plan management.
Radiotherapy has been reported to be a therapeutic option in the treatment of desmoplastic fibroma. Sanfilippo et al.  used 60Gy in 30 fractions to treat desmoplastic fibroma of the ilium, while Nag et al.  treated one patient with 45Gy in 25 fractions for desmoplastic fibroma to the distal femur. We have no experience in the use of adjuvant radiotherapy in the management of desmoplastic fibroma of bone at our institute.
Conflict of interest statement
Background Solitary adult myofibromas are infrequent lesions with a predilection for the head and neck [1,2]. The lesion is considered to be completely benign but there is the potential for it being confused with more aggressive spindle cell tumors. Histologically, myofibroma has two characteristic microscopic components: (a) a central, highly vascular and cellular, hemangiopericytoma-like component and (b) coalescent clusters and bundles of spindle-shaped myofibroblasts . Myofibromas usually occur as painless solitary masses, most often in the no donors and subcutaneous tissues of the head and neck . Most of these tumors present prior to the age of two years, but may be observed in older children and even in adults . Oudijk et al. have investigated 97 cases of MF and 17 cases of MMF and have shown that these lesions occur predominantly, but not exclusively, in infants and children . There are three distinct presentations : solitary, multicentric without visceral involvement and multicentric with visceral involvement. The solitary form tends to occur predominately in males  and is typically identified in the dermis, subcutis or deep soft tissues. The reported incidence of solitary osseous myofibromatosis is rare [2,7–10]. The distribution is predominantly on the head, neck and torso, with only a rare involvement of the extremities [4,5]. Wu et al. recently reported two cases of solitary osseous myofibromas in the upper extremities of two female infants older than two years of age . There are a few reports of myofibromas in adults [2,3,7,9,11–15]. Daimaru et al. reported five cases of myofibromas in adult patients . The tumors clinically presented as superficial, painless, and slowly enlarging nodules, usually of more than 10 years׳ duration, that occurred in the upper (two cases) and lower (two cases) extremities or the buccal mucosa (one case). However all of these tumors involved the dermis and subcutis, and did not develop in deeper structures.
Case report Radiographs of the tibia revealed a well-bordered lytic lesion with a sclerotic rim (Fig. 1). Computerized tomography (CT) scan of the proximal tibia showed an eccentric, purely lytic mass expanding into the proximal tibia with marginal sclerosis (Fig. 2). The lesion involved the anteromedial cortex, and yielded no evidence of a significant abnormality in the surrounding soft tissues. To rule out further tissue involvement a bone scan and a chest radiograph were performed, which failed to demonstrate any visceral or distant involvement. Histologically, the cells had a characteristic spindle shaped fibroblast appearance with pale pink cytoplasm and elongated nuclei when stained with hematoxylin and eosin (Fig. 3A, B). On immunohistochemical examination, the tumor cells were diffusely immunoreactive for smooth muscle actin (Fig. 3C). Immunostaining for Ki-67, a proliferation marker, showed a low proportion of Ki-67 positive cells, indicating a low tumor proliferation activity (Fig. 3D).