Soft tissue

Fibroblastic / myofibroblastic

Fibroma of tendon sheath



Last author update: 14 December 2021
Last staff update: 14 December 2021

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PubMed Search: Fibroma of tendon sheath [TI]

Zoonish Ashfaq, M.B.B.S.
Nasir Ud Din, M.B.B.S.
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Cite this page: Ashfaq Z, Anjum S, Ud Din N. Fibroma of tendon sheath. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuefibromatendon.html. Accessed July 5th, 2022.
Definition / general
  • Benign fibroblastic / myofibroblastic nodular proliferation usually attached to a tendon / tendon sheath
Essential features
  • Benign nodular, paucicellular spindle cell lesion with slit-like spaces mostly on finger tendon sheath
  • Cellularity may be higher at the periphery
  • Has the propensity to recur in 5 - 10% cases
ICD coding
  • ICD-O: 8810/0 - fibroma, NOS
  • ICD-11: EE6Y & XH0WB3 - other specified fibromatous disorders of skin & soft tissue and fibroma of tendon sheath
Epidemiology
Sites
  • Mostly on finger tendons
  • Intra-articular, rarely
Etiology
  • Not known at this time
Clinical features
Diagnosis
  • Diagnosis requires correlation of site with typical histological features
Radiology description
  • Plain Xrays show a soft tissue shadow without calcification or bone involvement
  • Ultrasound: well circumscribed hypoechoic mass
  • MRI: iso signal intensity to muscle on T1 weighted images, low signal intensity to muscle on T2 weighted images (BMC Musculoskelet Disord 2020;21:732)
Radiology images

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MRI

Prognostic factors
  • Benign lesion
  • Can recur in 5 - 10% cases
Case reports
Treatment
  • Surgical excision (marginal excision) is warranted in all cases
Clinical images

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Palmar surface

Multiple nonmovable deep seated nodules on palm

Gross description
Gross images

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Excised mass

Microscopic (histologic) description
  • Well circumscribed tumor of variable cellularity
  • Cellularity mostly higher at tumor edges
  • Bland spindle cells in a collagenous background
  • Tumor has characteristic thin walled slit-like vessels
  • Degenerative changes like myxoid / cystic change, osseous / chondroid metaplasia can be seen
  • Bizarre pleomorphic cells can also be present
  • Mitotically inactive
  • Necrosis not present
  • Cellular variant of fibroma of tendon sheath also exists; it overlaps morphologically with nodular fasciitis and fibrous histiocytoma (Cancer 1979;44:1945)
  • Reference: Geschickter: Tumors of Bone, 1949
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S.
Circumscribed nodular growth

Circumscribed nodular growth

Circumscribed spindle cell nodule

Circumscribed spindle cell nodule

Slit-like vessels

Slit-like vessels

Slit-like vascular spaces

Slit-like vascular spaces


Paucicellular lesion with collagenous stroma

Paucicellular lesion with collagenous stroma

Markedly collagenized stroma

Markedly collagenized stroma

Spindle cell proliferation

Spindle cell proliferation

Spindle cell lesion

Spindle cell lesion



AFIP images

Multinodular proliferation

Transition from collagenous to cellular area

Fibroblasts are bland and separated by collagen

Cellular area
resembles
leiomyosarcoma
or fibrosarcoma

Extensive
collagenization
of nodules

Most cases are
paucicellular
with scattered
spindled fibroblasts

Cytology description
  • H&E stained slides (J Cytol 2015;32:207):
    • Low cellularity
    • Few loose clusters and singly dispersed bland appearing fibrotic spindle cells and stellate cells admixed with hyalinized fibrocollagenous matrix
    • Necrosis and atypical mitoses not seen
Cytology images

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FNA

Positive stains
Electron microscopy images

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Organelles within a spindle cell

Densities of myofilament bundles

Cytoplasmic organelles

Spindled myofibrofibroblasts

Molecular / cytogenetics description
Sample pathology report
  • Finger nodule, excision:
    • Fibroma of tendon sheath (see comment)
    • Comment: Histology showed a well circumscribed, variably cellular lesion composed of bland spindle cells having regular nuclei arranged in sheets and fascicles. Thin walled vessels are present. The background is collagenous.
    • It is a benign condition with recurrence in 5 - 10% cases.
Differential diagnosis
  • Deep benign fibrous histiocytoma:
    • Involves extremities and head and neck region
    • Affects wide age range (i.e. 6 - 84 years)
    • Slight male predominance
    • Histologically well circumscribed and cellular lesion, prominent histiocyte-like cells, foam cells, giant cells and hemosiderin
    • IHC: CD34 positive
  • Tenosynovial cell tumor, localized type:
    • Present in hands; located in close proximity to synovium of tendon sheath or interphalangeal joint
    • Age range of 30 - 35 years
    • Female predominance
    • Histologically cellular tumor exhibiting variable composition of mononuclear cells, multinucleated giant cells, foamy macrophages, inflammatory cells and hemosiderin
    • IHC: positive for CD68, CD163 and CD45
  • Inclusion body fibromatosis:
    • Affects toes of children < 5 years of age
    • Ill defined, paucicellular, plump spindle cells exhibiting intracytoplasmic inclusion and bland nucleus with low mitotic activity
    • IHC: expresses SMA
    • Recurrence rate is high
Board review style question #1
What is the most common location for fibroma of tendon sheath?

  1. Face
  2. Fingers
  3. Oral cavity
  4. Pelvis
  5. Toes
Board review style answer #1
B. Fingers. The most common location for fibroma of tendon sheath is finger tendons (i.e. thumb, index finger and middle finger).

Comment Here

Reference: Fibroma of tendon sheath
Board review style question #2

A 32 year old man has had painless swelling in the palm of his hand for 6 months. It was excised and the histology is shown in the above image. What is the most likely diagnosis?

  1. Benign fibrous histiocytoma
  2. Fibroma of tendon sheath
  3. Nodular fasciitis
  4. Palmar fibromatosis
  5. Tenosynovial giant cell tumor, localized type
Board review style answer #2
B. Fibroma of tendon sheath

Comment Here

Reference: Fibroma of tendon sheath
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