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What is Ischemic fasciitis and explain in detail?
Ischemic fasciities (IF), also termed atypical decubital fibroplasia or decubital ischemic fasciitis, is a rare pseudosarcomatous (i.e. easily mistaken for a sarcoma) tumor. It was first described by E. A. Montgomery et al. in 1992. This tumor typically forms in the subcutaneous tissues (i.e. lower most tissue layer of the skin) that overlie bony protuberances such as a hip in individuals who are debilitated and bed-ridden.Microscopically, IF lesions consist of proliferating, atypical fibroblasts and/or myofibroblasts. The lesions were initially regarded as non-neoplastic proliferation responses of these cell types to long-term tissue pressure or trauma. More recently, however, the World Health Organization, 2020, defined IF lesions as neoplasms, i.e. tissue growths which are uncoordinated with that of the normal surrounding tissue and persist in growing even if the original trigger for their development is removed. The Organization formally classified IF lesions as belonging to the category of benign fibroblastic and myofibroblastic tumors.The treatment of choice for these often disfiguring, uncomfortable, and/or painful IF tumors is generally conservative, local surgical excision. It is critically important that these benign tumors be distinguished from other fasciitis tumors as well as certain sarcomas which can be highly invasive and/or malignant and therefor require far more aggressive treatment.

Presentation
In the original study of IF, individuals diagnosed with the disorder were women (16 cases) or men (12 cases) age 15 to 95 years; In a more recent study, diagnosed individuals were women (15 cases) or men (29 cases) aged 23–96 years old. Most individuals in these two studies were in their 8th or 9th decade when diagnosed with IF and, overall, had a relatively long history of being invalided, immobilized, and/or bed-ridden due to other disorders such as severe osteoarthritis, rheumatoid arthritis, chronic renal failure, chronic obstructive pulmonary disease, cancer, or dementia. In the study of 44 individuals, however, an appreciable number of patients did not have a history of debilitation. Some individuals reported that they had prior trauma in the areas where their lesions developed.Individuals present with a painless or painful and sometimes disabling slowly growing mass that is ill-defined, located in deep subcutaneous tissues, and, rarely, has spread into an adjacent skeletal muscle or tendon. The masses vary from 1.3 to 10 cm in maximum diameter. In the study of 44 cases, 76.7% of the tumors were located around the base of a hip (11 cases), shoulder (7 cases), or greater trochanter of the femur; 4 were in a hip joint, 4 in a thigh, 3 in the iliac crest, 2 in a buttock, and 1 each in the lumbar region, scapular region, or a deltoid muscle; in the remaining cases, ~11.2% of the tumors were on the chest wall away from the shoulders and ~11.2% were on the back. Typically, the tumors reside over boney protuberances which, it is thought, provide the mechanical pressures that cause poor blood flow to nearby subcutaneous tissues, aberrant wound healing in these tissues, and thereby the development of IF.

Pathology
On gross examination, IF tumors are typically white-yellow masses with central necrosis (i.e. areas of dead or dying cells), and areas containing cysts  and/or old, dried hemorrhages. The tumors are often poorly circumscribed, have an infiltrative appearance, may be multinodular, and lie in subcutaneous tissue but may also involve the dermal layer of the skin and/or the reticular dermis. Microscopic histopathological studies of IF tissues report the characteristic presence of a distinct zonal appearance, i.e. the presence of central zones of fibrinoid necrosis and areas of cyst-laden necrosis in a hypocellular background surrounding by a zone of granulation tissue (i.e. connective tissue containing microscopic blood vessels) populated by atypical, swollen fibroblasts, myofibroblasts, and/or macrophages.Immunohistochemistry analyses of IF tumors often show the presence of fibroblasts, fibroblast-like cells, and or other types of cells that in a percentage of cases express smooth muscle actin proteins, CD68 protein,. desmin protein, vimentin protein, and collagen type IV protein, but not keratin, S100, calponin, or CD34 proteins. The finding that a tumors cells have some of these patterns of protein expression can help support the diagnosis of IF.

Gene and chromosome abnormalities
A single case of IF was found to have tumor cells bearing chromosomal translocations between chromosomes 1 and 2 and/or chromosomes 7 and 19