Skin nonmelanocytic tumor
Fibrous, fibrohistiocytic and myofibroblastic neoplasms
Collagenous fibroma
Author: Hillary Rose Elwood, M.D.
Last author update: 1 April 2017
Last staff update: 29 March 2023
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Collagenous fibroma
Table of Contents
Definition / general | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Immunohistochemistry & special stains | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Elwood HR. Collagenous fibroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticcollagenousfibroma.html. Accessed June 10th, 2023.
Definition / general
- Also called desmoplastic fibroblastoma
- Benign soft tissue tumor that usually occurs in the subcutis or skeletal muscle, rarely dermal involvement
- Typically arises in 5th or 6th decade of life, slowly growing mass, 4 cm or less in size
- Arise more commonly in men
- Most common location is upper extremity
Case reports
- 65 year old man with mass on index finger (Arch Plast Surg 2012;39:84)
- Cutaneous desmoplastic fibroblastoma (J Cutan Pathol 1998;25:450)
Microscopic (histologic) description
- Well circumscribed hypocellular lesion
- Bland stellate and spindled fibroblasts with prominent collagenous to myxoid matrix
- No necrosis and minimal or absent mitoses
- Can have scattered blood vessels, sometimes with perivascular hyalinization
Microscopic (histologic) images
Contributed by Hillary Elwood, M.D.
Hypocellularity
Prominent collagenous stroma, scattered bland stellate and spindled fibroblasts
Immunohistochemistry & special stains
- Not necessary for diagnosis
- Lesional cells can have focal staining for smooth muscle actin and factor XIIIa
- Lesional cells are negative for S100, pancytokeratin, CD34, desmin
Differential diagnosis
- Neurofibroma:
- S100+; neural cells in myxoid stroma
- Fibromatosis:
- Much more cellular, often fascicular growth pattern
- Elastofibroma:
- Typically on shoulder, has prominent wavy elastic fibers
Board review style question #1
Which of the following is TRUE of collagenous fibroma:
A. S100+
B. Usually arises in the subcutis
C. Hypercellular, infiltrative soft tissue tumor
D. Most commonly occurs in children
E. Metastasis common
A. S100+
B. Usually arises in the subcutis
C. Hypercellular, infiltrative soft tissue tumor
D. Most commonly occurs in children
E. Metastasis common
Board review style answer #1
B. Collagenous fibroma is a benign soft tissue tumor that usually arises in the subcutis, with dermal involvement less common. The lesion is hypocellular, well circumscribed and most commonly occurs in adults. S100 immunostain is negative within lesional cells.
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Reference: Collagenous fibroma
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Reference: Collagenous fibroma
