Fibroblastic/myofibroblastic tumours

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This article covers fibroblastic/myofibroblastic tumours. These tumours fit into the larger category of soft tissue lesions.

List of tumours

Benign

WHO classification:[1]

Locally aggressive

WHO classification:[1]

Occasionally metastasizing

WHO classification:[2]

Malignant

WHO classification:[2]

Non-malignant

Proliferative fasciitis

General

  • Benign.
  • May mimic a sarcoma.[3]

Clinical:

  • Solid subcutaneous nodule.
  • Rapid growth.
  • May be painful.

Gross

  • Classically upper and lower extremities.[3]
  • Poorly demarcated.

Microscopic

Features:[4]

  • Large polygonal (ganglion-like) and/or spindled cells with:
    • Vesicular (clear) nuclei.
    • Prominent nucleoli.
  • +/-Binucleation.
  • Loose myxoid stroma.
  • Frequent typical mitoses.
    • No atypical mitoses.

DDx:

Images:

Proliferative myositis

General

  • Benign.
  • Possible arise from pericytes.[6]

Microscopic

Features:[6][7]

  • Large ganglion-like cells.
    • Cells have single prominent nucleolus.
  • Spindle cells.
  • +/-Binucleation.
  • Mitotic activity.
    • No atypical mitoses.

Image:

IHC

Features:[6]

  • Vimentin +ve.
  • SMA +ve.
  • Desmin +ve/-ve.

Others:[6]

  • Factor XIIIa -ve.
  • S100 -ve.
  • CAM5.2 -ve.
  • NSE -ve.

Elastofibroma

General

  • Benign.
  • Classically, subscapular in elderly women.[8][9]

Gross

Features:

  • Yellow-white, moderate demarcation to surrounding tissue.[10]

DDx - shoulder lesions:

Microscopic

Features:

  • Thick bundles of collagen.
  • Elastin fibres.

Image:

Nodular fasciitis

Not to be confused with necrotizing fasciitis.

General

  • Benign.
  • All age groups.
  • Associated with trauma.

Microscopic

Features:[11][12]

  • Usu. well-circumscribed.
  • Clusters of (non-pleomorphic) spindle cells.
  • Inflammation (lymphocytes).
  • Microcysts in cellular regions - uncommon - discriminatory.
  • Mitoses - common.
  • Extravasated RBCs.

The BD feature list:[13][14]

  • Tissue culture-like/CNS-like morphology.
  • Thick (keloid-like) collagen bundles - key feature.
  • Extravasated RBCs.
  • Inflammation.
  • +/-Giant cells.

Notes:

  • No significant nuclear atypia.
  • No atypical mitoses.
  • May be cellular.

DDx:[15]

Images:

IHC

Routine spindle cell panel:

  • CD34 -ve.
  • Desmin -ve.
  • SMA -ve.
  • S100 -ve.
  • AE1/AE3 -ve.

Others:

  • H-caldesmon -ve.
  • EMA -ve.
  • Vimentin +ve.

Molecular

  • Evolving - case reports.
    • t(15;15)(q13;q25).[16]

Desmoid-type fibromatosis

  • AKA desmoid tumour.
  • AKA desmoid fibromatosis.

General

Microscopic

Features:[18][19]

  • "Sweeping fascicles"/bundles.
  • Spindle cells with:
    • Small slender nuclei.
    • Solid dark eosinophilic cytoplasm.
  • +/-Mitoses - may be abundant.
  • Long thin-walled vessels - parallel to one another - important feature.

Notes:

Images:

IHC

Features:[18]

  • Beta-catenin +ve - important.
  • SMA +ve ~50% of lesions.

Lipofibromatosis

  • AKA infantile subcutaneous fibromatosis.

General

  • Childhood.

Microscopic

Features:[18]

  • Fibroblastic cells surrounding adipocytes.

Image:

IHC

Features:[18]

  • CD34 +ve.
  • BCL2 +ve.
  • S100 +ve.
  • CD99 +ve.
  • Actin +ve.
  • EMA +ve.

Desmoplastic fibroblastoma

General

  • Benign lesion.

Epidemiology:

  • May be on the lip.
  • Male:female ~= 5:1.[22]
  • Age - typically 40s & 50s.[22]

Gross

  • Classically found in the shoulder region.

Microscopic

Features:[23][24]

  • Spindle cells or stellate cells without nuclear atypia.
  • Acellular stroma with abundant collagen - key feature.
  • +/-Myxoid areas.
  • +/-Rare mitoses.

DDx:[23]

Images:

IHC

Features:[23]

Molecular

  • llq12 breakpoint described as being characteristic -- possibly the FOSL1 gene.[26]

Calcifying fibrous tumour

General

  • Rare.
  • Benign.

Microscopic

Features:[27]

  • Submucosal circumscribed fibrocollagenous nodule.
  • Psammomatous calcifications.
  • Focal plasma cells at the periphery.

Myofibroma

General

  • Benign.
  • Often < 2 years old; however, may be seen in adults.
  • Not common.[28]

Gross

  • Classically (oral) locations: tongue, buccal mucosa, lip.[28]

Microscopic

Features:[28]

  • Spindle cells with:
    • Tapering nuclei.
    • Eosinophilic cytoplasm.

Note:

DDx:

IHC

Features:[28]

  • Vimentin +ve.
  • SMA +ve.
  • S-100 -ve,

Cellular angiofibroma

General

Gross

Features:[30]

  • Superficial.
  • Well-circumscribed.

Classic location:

Microscopic

Features:[30]

  • Spindle cell lesion.
  • Many small-to-medium blood vessls.

IHC

Features:[30]

  • CD34 ~50% of cases.
  • SMA ~41% of cases.
  • CD99 -ve.
  • EMA -ve.

Occasionally metastasizing

Inflammatory myofibroblastic tumour

  • AKA inflammatory pseudotumour, AKA inflammatory fibrosarcoma,[31] AKA plasma cell granuloma.[32][33]

General

  • Mostly benign.
  • Children & young adults.
  • Classically located in mesentery of ileocolic region or small bowel.[31]

Microscopic

Features:[31]

  • Inflammation:
  • Spindle cells without atypia.
  • +/-Fasciular architecture.
  • Mitoses -- though none atypical.
  • +/-Necrosis.
  • +/-Hemorrhage.
  • Calcifications.

DDx:

Notes:

  • Some consider this a wastebasket diagnosis... for benign appearing spindle cell lesions.[35]

Images:

IHC

Features - dependent on site:

  • SMA +ve.[36]
  • Vimentin +ve.

Variable staining with:

Negative:[36]

  • S100, CD117, CD68.

Molecular

  • ALK rearrangements.[34]

Low-grade myofibroblastic sarcoma

General

  • Rare ~ 100 cases in the literature.
  • Usu. oral cavity or extremities.[38]

Microscopic

Features:

  • Spindle cells in the storiform pattern[38] or in fasicles.
  • Rare mitoses.

Images:

DDx:

IHC

  • SMA +ve.
  • CD34 -ve.
  • CD117 -ve.[38]
  • H-caldesmon -ve.[38]


Congenital-infantile fibrosarcoma

Should not be confused with adult fibrosarcoma.

General

  • Locally aggressive.

Microscopic

Features:[39]

  • Spindle cell lesion.

Molecular

Characteristic translocation:[40]

Solitary fibrous tumour

  • Abbreviated SFT.

General

  • Grouped with hemangiopericytoma in the WHO classification - as it is thought to be the same tumour.[18]
  • May be benign or malignant; more commonly benign.[41][42]
  • May be associated with hypoglycemia.
    • Known as Doege-Potter syndrome.[43]

Gross

Microscopic

Features - benign:

  • Spindle cells in a patternless pattern.
  • Hemangiopericytoma-like area (staghorn vessels).
  • Keloid-like collagen bundles - key feature.
  • Usually well-circumscribed.

Criteria for malignancy:[18]

  • Necrosis.
  • Mitoses >4/10 HPF -- definition suffers from HPFitis.
  • Increased cellularity.
  • Marked nuclear atypia.
  • Infiltrative margin.

Images:

IHC

  • CD34 ~90% +ve.
  • CD99 ~70% +ve.
  • BCL2 ~50% +ve.

Hemangiopericytoma

General

  • Grouped with solitary fibrous tumour in the WHO classification; possibly the same tumour (?).[18]
  • Arises from the pericyte, a connective tissue cell of small vessels that is thought to be involved in flow regulation.
  • Hematologic spread most common - to lungs.[44]
  • Oncogenic osteomalacia - assoc. with hemangiopericytoma.[44]

Presentation

  • Usually painless mass, slow enlargement.

Radiology

  • Intramedullary lytic mass.
  • May be well-circumscribed.
  • +/-Periosteal reaction.
  • +/-Sclerotic border.

May be worked-up with angiography to distinguish from a vascular malformation.[45]

Location

  • Usually extremities - femur or proximal tibial.[44]

Microscopic

Features:[45]

  • Hypervascular lesion - key diagnostic feature.[46]
    • Abundant thin-walled branching small vessels of variable size.
      • May be described as "staghorn vessels" or "antler-like" vasculature.
      • Cells may "onion-skin" around thin blood vessels.
  • Spindle or ovoid shaped cells in nests or sheets.

DDx:

IHC

Features:[18][46]

  • Vimentin +ve (usually).
  • Desmin -ve (typical).
  • Factor VIII -ve (marks endothelium).
  • CD34 +ve.
    • CD34 usu. -ve in synovial sarcoma.
  • CD31 -ve (marks benign endothelium).
  • vWF (von Willebrand factor) -ve.

May be in the DDx for meningioma:[47]

  • EMA -ve.
  • S100 -ve.

Malignant

Low-grade fibromyxoid sarcoma

  • AKA hyalinizing spindle cell tumour.
  • Should not be confused with myxofibrosarcoma.
  • Abbreviated LGFMS.

General

  • Deep soft tissue.
  • Related to hyalinizing spindle cell tumour with giant collagen rosettes.[48]

Microscopic

Features:[49]

  • Myxoid stroma alternating with fibrogenic areas - key feature.
  • Low cellularity.
  • Spindle cells.
  • +/-Rosette of collagen with central hyaline core.[50]

Notes:

  • Few/absent mitoses.

DDx:

Images:

IHC

Features:[50]

  • EMA +ve.
  • CD99 +ve.
  • BCL2 +ve.

Others:[50]

  • SMA -ve.
  • S100 -ve.
  • Desmin -ve.

Molecular pathology

Adult fibrosarcoma

General

  • Malignant.
  • Older adults.
  • Locations: head & neck, extremities.

Microscopic

Feature:[50]

  • Spindle cell lesion.
  • Herring bone pattern - key feature.
  • Mitoses.

DDx (herring bone):

  • MPNST.
  • Synovial sarcoma.
  • Fibrosarcoma.

DDx:

Images:

IHC

Features:[50]

  • Vimentin.
  • SMA.

Myxofibrosarcoma

General

  • Malignant.
  • Usu. older people, superficial (skin/dermis) and extremities (arm, legs).[53][54]

Microscopic

Features:[53]

  • Discontinuous fibrous septae.
  • Myxoid background.
  • Variable cellularity and nuclear pleomorphism.
  • Spindle cells or epithelioid cells.[54]
  • Curvilinear vessels.[54]

DDx:

Image:

IHC

  • Vimentin +ve -- otherwise non-distinctive.[53]

See also

References

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