Table of Contents
Definition / general | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: DePond WD. Myofibroblastoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lymphnodesmyofibroblastoma.html. 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
- 45 year old woman with solitary spindle cell tumor with myoid differentiation of the lymph node (Arch Pathol Lab Med 1989;113:547)
- 49 year old woman with recurrent intranodal palisaded myofibroblastoma with metaplastic bone formation (Arch Pathol Lab Med 1999;123:433)
- 62 year old man with supraclavicular mass (University of Pittsburgh: Left Supraclavicular Mass [Accessed 22 June 2018])
- 71 year old man with inguinal mass (Arch Pathol Lab Med 2003;127:1040)
- Patient with intranodal myofibroblastoma in a submandibular lymph node (Am J Clin Pathol 1992;97:69)
Treatment
- 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
surrounding
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
- Spindle cells: smooth muscle actin, vimentin, variable factor XIIIa
- Amianthoid fibers: elastic stains, trichrome, collagen type I / III, smooth muscle actin
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
