Lymph nodes & spleen, nonlymphoid
Lymph nodes-nonlymphoid neoplasms

Topic Completed: 1 June 2006

Minor changes: 29 July 2020

Copyright: 2003-2020,, Inc.

PubMed Search: Myofibroblastoma[TI] lymph nodes

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Cite this page: DePond W. Myofibroblastoma. website. Accessed August 7th, 2020.
Definition / general
  • Also called palisaded myofibroblastoma, intranodal hemorrhagic spindle cell tumor with amianthoid fibers
  • Initially described in 1989 (Am J Surg Pathol 1989;13:347, Am J Surg Pathol 1989;13:341)
  • Amianthoid: having a crystalline appearance like asbestos
  • Rare; may derive from myofibroblasts (Pathol Int 1998;48:307)
  • Often solitary, painless inguinal lymph node in adult; also neck and mediastinum
  • Benign behavior with only rare recurrence; does not metastasize
Case reports
  • Excision
Gross description
  • Well circumscribed, up to 5 cm
  • Gray-white-tan with hemorrhage
Microscopic (histologic) description
  • May have rim of compressed normal tissue
  • Intersecting bundles of uniform bland spindle cells with myofibroblastic or smooth muscle differentiation, including scant eosinophilic cytoplasm with perinuclear vacuoles and bland fusiform nuclei
  • Focal nuclear palisading may occur
  • Prominent interstitial hemorrhage and hemosiderin
  • Amianthoid fibers (strongly eosinophilic, stellate, extracellular matrix deposits composed of crystalline fibers) may be present with variable calcification and surrounded by mast cells
  • No / rare mitotic figures, no atypia, no slit-like vascular spaces, no extravasated red blood cells
Microscopic (histologic) images

AFIP images:

Palisaded myofibroblastoma

Contributed by Mark R. Wick, M.D.

Palisaded type

Images hosted on other servers:

Palisaded tumor with amianthoid fibers

Various images

Fascicles of elongated
cells with pale
cytoplasm and
tapered nuclei

Amianthoid fibers composed
of central vessel surrounded
by core of collagen with
peripheral spokes, van Gieson+

Mast cells
amianthoid fibers
are methylene blue+

Interstitial cells are smooth muscle actin+

Actin stains smooth
muscle cells and
spokes of amianthoid
fibers (arrows)

Early amianthoid fiber formation, in which a vessel
is beginning to be surrounded by collagen; overlaying
it is an almost fully formed amianthoid structure;
both are surrounded by proliferating myofibroblasts

Cytology description
  • Moderately cellular with benign appearing, dissociated, single spindle cell with elongated nuclei, pointed ends and occasional twisted forms
  • In pale fibrillary matrix with hemosiderin granules, no atypia (Acta Cytol 2002;46:1143)
Positive stains
Negative stains
Electron microscopy description
  • Pinocytotic vesicles, microfilament aggregates, well developed rough endoplasmic reticulum with dilated cisternae
  • Amianthoid fibers contain collagen fibrils arranged in orderly parallel fashion, long, frequently indented nuclei (Ultrastruct Pathol 1996;20:79)
Electron microscopy images

Images hosted on other servers:

Spindle cell with indented nuclei and parallel collagen fibrils

Differential diagnosis
  • Benign metastasizing leiomyoma: smooth muscle cells are more ovoid with more prominent eosinophilic cytoplasm, no hemorrhage, no amianthoid fibers
  • Dendritic cell sarcoma: nests or whorls of plump cells with scattered inflammatory cells, no prominent hemorrhage, no amianthoid fibers, CD21+, CD35+
  • Intranodal schwannoma: distinct biphasic pattern, S100+
  • Kaposi sarcoma: curved fascicles of spindle cells with atypia and PAS+ hyaline globules, brisk mitotic activity, slit-like vessels with extravasated red blood cells
  • Spindle cell carcinoma, melanoma or sarcoma: atypia and mitotic figures
Additional references
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