Finger fibromas
Common benign lesions often of the annular pulleys associated with finger triggering
Nodular fasciitis
This is a pseudotumour occurring in the third to fifth decade. Half of the cases involve the volar aspect of the forearm followed by the lower limb head and neck. A feature is a rapid growth rate. There is mild pain in some patients. Three variants are described subcutaneous, fascial and intramuscular, with that order of frequency. The subcutaneous form is by far the most common on imaging there is also occasional calcification and ossification. On MRI, the lesions are slightly hyperintense to muscle on T1 weighted images and high signal on T2. Enhancement occurs which may be either diffuse or peripheral. Superficial lesions are noted to have higher signal on T2 weighted images with more intermediate signal and signal heterogeneity with the deeper intramuscular lesions. Thickening of the adjacent fascia forming a tail is reported. There are two variants of this condition one that involves vessels called intravascular fasciitis and one that involves soft tissues overlying bony prominences called ischemic fasciitis. Other variants include proliferative fasciitis and proliferative myositis.
Desmoplastic Fibroma
These lesions are large, subcutaneous and occur in the upper extremities in males in the fifth to seventh decade.
Fibromatoses
The most common fibrous tumour in children is myofibromatosis, which is characterised by multiple nodules throughout the skin, bone, muscles and visera. In children these lesions may be solitary or multiple. The solitary lesion is related to infantile hemangiopericytoma. Small foci of calcification maybe present within the lesions. Within bone they are lytic lobulated and geographic with a little sclerosis. Related conditions include juvenile hyaline fibromatosis, Winchester Syndrome and fibromatosis colli.
Infantile Fibromatosis
.. fibrous thickening of muscle or fascia involving the head and neck typically presents the first two years of life. The lesion is also referred to aggressive infantile fibromatosis. Calcifying aponeurotic fibroma occurs in the first two decades of life. It involves the palms and soles of the feet. It is a self limiting lesion stippled calcification secondary erosion of bone males have been noted
Fibromatosis Plantar fibroma
A group of soft tissue lesions characterised by proliferation of benign fibrous tissue with variable growth patterns. The best known is Dupuytren’s disease associated with thickening of the palmar fascia with contracture. It is very common with 1%-2% of the general population affected. Men are affected more commonly than women and the lesions are not infrequently bilateral. An ultrasound examination is the most useful imaging demonstrating alteration in the signal characteristics of the subcutaneous tissue superficial to the flexor tendons. Intermediate signal intensity and T1 and T2 weighted images may imply a more active cellular matrix and an increased likelihood of recurrence. Plantar fibroma are bilateral in 20%-50% of patients. Diabetes, epilepsy and liver disease all predispose.
Agressive Fibromatosis
..a group that also includes abdominal wall and intra-abdominal fibromatosis. The commonest locations are the shoulder and upper arm, chest wall, thigh, lower leg and forearm. On MRI the lesions are deep, intermuscular and demonstrate decreased signal intensity on most pulse sequences. The lesions generally do not enhance. Extension along the fascia is a useful sign.
Xanthoma
These are accumulations of histiocytes containing lipids and are most commonly associated with hyperlipidaemic syndromes. The most common is seen in the skin and subcutaneous but frequently involve tendon synovium and bone. The fingers, wrists and ankles are the commonest locations. The lesions generally regress when the underlying hyperlipidaemia is treated.