This is a very rare phenomenon (50 years of age), and more commonly in women than men (5:1). There is an increased frequency in Okinawa, Japan, but this may be a reporting bias. The tumor develops very specifically in the subscapular or infrascapular area, deep to the muscle, sometimes even attached to periosteum of ribs. It is usually between the shoulder blade and the lower neck, with rare tumors reported in the chest wall.
Elastofibroma dorsi
Dermatofibroma
Aggressive infantile fibromatosis
Dermatofibrosarcoma protuberans
Diffuse infantile fibromatosis
Aggressive fibromatosis
Acral fibrokeratoma
Superficial acral fibromyxoma