Collagenous fibroma (desmoplastic fibroblastoma): a clinicopathologic analysis of 63 cases of a distinctive soft tissue lesion with stellate-shaped fibroblasts.
Sixty-three cases of collagenous fibroma (desmoplastic fibroblastoma) from the files of the Armed Forces Institute of Pathology were analyzed. These tumors occurred mostly in men (80%) with a median age of 50 years (range, 16 to 81 years). The lesions had a wide anatomic distribution and involved the arm (24%), shoulder girdle (19%), posterior neck or upper back (14%), feet or ankles (14%), leg (14%), hand (8%), and abdominal wall and hip (6%). The patients typically presented with a history of a painless, slowly growing mass, often of relatively long duration. The tumors ranged in size from 1 to 20 cm (median, 3.0 cm). The lesions were predominantly subcutaneous, but fascial involvement was common, and 27% of cases involved skeletal muscle. Gross examination typically showed an elongated, lobulated, or disc-shaped mass with a firm consistency and a homogeneous pearl-gray color. Histologically, the tumors often appeared well marginated on low-power examination, but most (78%) infiltrated fat or, less commonly, skeletal muscle. The lesional cells were relatively bland stellate and spindle-shaped fibroblasts separated by a collagenous or myxocollagenous matrix. Mitotic activity was absent or minimal. Some of the lesional cells had a myofibroblastic immunophenotype, as evidenced by focal reactivity for muscle-specific and alpha-smooth muscle actins. In a few cases, rare actin-positive cells were also positive for keratins. Desmin, S100 protein, and CD34 were not expressed. None of the 39 patients with follow-up (median, 11 years) developed a recurrence. Collagenous fibroma is a benign fibroblastic/myofibroblastic proliferation. The large size of some of these tumors coupled with slow growth and persistence favors a neoplastic process over a peculiar reactive proliferation. The differential diagnosis includes a variety of reactive and neoplastic fibroblastic lesions, most importantly fibromatosis and low-grade fibromyxoid sarcoma. Simple, conservative excision is the treatment of choice for collagenous fibroma.
Armed Forces Institute of Pathology, Department of Soft Tissue Pathology, Washington, DC 20306-6000, USA.
M
M
Miettinen
J F
JF
Fetsch
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005350:Fibroma / Q000175:diagnosis; D018220:Fibroma, Desmoplastic / Q000378:metabolism / Q000473:pathology*; D005354:Fibrosarcoma / Q000175:diagnosis; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000473:pathology*
D003598:Cytoskeletal Proteins