Collagenous fibroma (also known as desmoplastic fibroblastoma) is a slow-growing, deep-set, benign fibrous tumor, usually located in the deep subcutis, fascia, aponeurosis, or skeletal muscle of the extremities, limb girdles, or head and neck regions.^[1]: 605 The World Health Organization in 2020 reclassified desmoplastic fibroblastoma/collagenous fibroma as a specific benign tumor type within the broad category of fibroblastic and myofibroblastic tumors.^[2]