Soft tissue

So called fibrohistiocytic

Giant cell tumor of soft tissue



Topic Completed: 3 September 2021

Minor changes: 3 September 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Giant cell tumor of soft tissue [TIAB]

Carina Dehner, M.D., Ph.D.
Louis P. Dehner, M.D.
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Cite this page: Dehner C, Dehner LP. Giant cell tumor of soft tissue. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuegct.html. Accessed September 21st, 2021.
Definition / general
  • Tumor of low malignant potential that is considered the soft tissue analog of giant cell tumor of bone (Mod Pathol 1999;12:894)
Essential features
  • Giant cell tumor of soft tissue (GCT-ST) is morphologically identical to giant cell tumor of bone
  • Tumor of low grade malignant potential, which is cured by complete surgical resection
  • Lacks mutations in the H3F3A gene, which makes it distinct from giant cell tumor of bone
Terminology
  • Soft tissue giant cell tumor of low malignant potential
  • Giant cell tumor of soft parts
  • Extraskeletal giant cell tumor, osteoclastoma of soft tissue (not recommended or commonly used)
ICD coding
  • ICD-0: 9251/1 - giant cell tumor of soft parts, NOS
  • ICD-10: D48.1 - neoplasm of uncertain behavior of connective and other soft tissue
Epidemiology
  • Rare benign neoplasm, exact incidence unknown
  • M = F
  • Age average ~40 years (range: 1 - 86 years)
  • Can be associated with Paget disease of bone (Diagn Cytopathol 1998;19:352)
Sites
  • Arms, hand and thighs are most common sites (Mod Pathol 1999;12:894)
  • May develop in superficial or deep soft tissue
  • May present multifocal
Clinical features
  • Painless mass
Diagnosis
  • Indistinguishable from giant cell tumor of bone in the absence of radiology or clinical information
Radiology description
  • Soft tissue mass
  • Mineralization in some cases
  • May present as cystic lesion with internal nodules; nonspecific soft tissue changes adjacent
  • Reference: BJR Case Rep 2020;6:20200012
Radiology images

Images hosted on other servers:

B: T1 weighted image of cystic mass
C: T2 weighted nodule within cyst
D: Contrast enhanced T1 image of mass

Prognostic factors
  • Conservative surgical resection with negative margins is curative in the majority of cases
  • Local recurrence rate approximately 6 - 10%
  • Lymph node metastasis and distant metastasis very uncommon
  • Single cases of malignant GCT-ST with metastases have been reported (Am J Surg Pathol 2000;24:248, Am J Surg Pathol 2000;24:386)
Case reports
Treatment
  • Surgical resection is curative
Clinical images

Images hosted on other servers:

54 year old man

Firm, polypoid nodule

Gross description
  • Up to 10 cm, usually dermis or subcutis, 30% are below superficial fascia
  • Well circumscribed, nodular, fleshy, red-brown-gray, gritty at periphery due to calcification
Gross images

Images hosted on other servers:

Gross specimen of GCT-ST

Microscopic (histologic) description
  • Tumors present as multinodular lesions diffusely infiltrating soft tissue
  • Tumor nodules consist of a mix of bland, round to oval mononuclear cells, spindle cells and multinucleated giant cells of osteoclast type
  • Spindle cells may be arranged in a storiform or fascicular pattern
  • Tumors commonly have a peripheral rim of metaplastic bone that may extend to the center
  • Hemorrhage and cystic areas, consistent with secondary aneurysmal bone cyst-like changes, are commonly appreciated
  • Significant atypia will exclude this diagnosis, however, mitotic activity is commonly seen and may be brisk
  • Vascular invasion is seen in up to 50% of cases (Mod Pathol 1999;12:894)
  • Necrosis is uncommon
Microscopic (histologic) images

Contributed by Carina Dehner, M.D., Ph.D.

Well circumscribed lesion

Subcutaneous lesion

Minimal atypia

Spindling of cells


Giant, mononuclear and spindle cells

Mononuclear cells

Epithelioid cells

Lobulated lesion

Cytology description
  • Mononuclear stromal cells have oval to spindle shaped nuclei with ill defined cytoplasm lacking significant atypia
  • Osteoclast type giant cells are evenly distributed throughout the lesion with bland, vesicular nuclei
  • Reference: J Cytol 2009;26:33
Cytology images

Images hosted on other servers:

Multinucleated giant cells

Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Soft tissue, left arm, excision:
    • Giant cell tumor of soft tissue, 3.5 cm, involving dermis and subcutis (see comment)
    • Comment: Provided hematoxylin and eosin stained sections show a well circumscribed, multinodular tumor composed of sheets of evenly distributed, multinucleated giant cells of osteoclast type. The latter are intervened by abundant mononuclear cells, some of which show spindling. Immunohistochemical studies (single stain antibody procedure with adequate controls) show that tumor cells are positive for SMA (patchy) and CD68, while negative for S100 protein, CD45 and desmin. An immunohistochemical study for H3K34W is negative, ruling out a metastasis of giant cell tumor primary to the bone. Morphologic and immunohistochemical studies support the diagnosis of giant cell tumor of soft tissue.
Differential diagnosis
Board review style question #1

The tumor shown in the image above presented as a subcutaneous mass in the arm. What is the diagnosis?

  1. Giant cell tumor of bone
  2. Giant cell tumor of soft tissue
  3. Tenosynovial giant cell tumor, localized type
  4. Undifferentiated pleomorphic sarcoma
Board review style answer #1
B. Giant cell tumor of soft tissue presents as subcutaneous lesion rather than a bone lesion (therefore, A is wrong). It has a peripheral shell of metaplastic bone (which distinguishes it from C) and is not as atypical as D.

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Reference: Giant cell tumor of soft tissue
Board review style question #2
What genetic aberration may be helpful to distinguish primary giant cell tumor of soft tissue from a metastasis of a giant cell tumor of bone?

  1. Lack of a mutation in H3F3A
  2. Presence of a mutation in H3F3A
  3. Presence of a mutation in CSF1
  4. Presence of a mutation in H3K36M
Board review style answer #2
A. H3F3A mutations can be found in giant cell tumor of bone but not in giant cell tumor of soft tissue. CSF1 is the molecular feature of tenosynovial giant cell tumor and H3K36M is the mutation found in chondroblastoma.

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Reference: Giant cell tumor of soft tissue
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