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Table 1: Summary of the clinical, radiographic, and pathological characteristics of the tumors in the differential for collagenous fibroma.

Tumor type Age, gender Location Imaging Histology Collagenous fibroma Mainly males, between fifth and seventh decades of life Extremities Well-circumscribed Hypocellular, with prominent collagenous background, entrapment of the soft tissue at the periphery. Desmoid tumor (extra-abdominal) Puberty-middle age, no gender predilection Shoulder, chest wall, back, thigh, head and neck Poorly defined Variably cellular stroma containing compressed or distorted blood vessels Gardner’s fibroma Children, adolescents, no gender predilection Paraspinal region, back, chest wall, flank, head and neck, extremities Poorly defined Hypocellular, entrapment of the soft tissue at the periphery. Not vascular. Nuchal-type fibroma Third through fifth decades of life, male predilection Classically in the posterior neck Poorly defined Hypocellular, with haphazardly arranged collagen fibers, nerve twigs.