Lymph nodes & spleen, nonlymphoma

Lymph node & spleen-nonlymphoid neoplasms


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Last staff update: 29 July 2022

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PubMed Search: Myofibroblastoma[TI] lymph nodes

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Cite this page: DePond WD. Myofibroblastoma. website. Accessed June 5th, 2023.
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

Contributed by Mark R. Wick, M.D. and AFIP images

Palisaded type

Palisaded myofibroblastoma

Images hosted on other servers:

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)
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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