Soft tissue
Fibroblastic / myofibroblastic
Intranodal palisaded myofibroblastoma
Last author update: 1 April 2013
Last staff update: 23 June 2021
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Intranodal palisaded myofibroblastoma
Table of Contents
Definition / general | Terminology | Epidemiology | Sites | Pathophysiology | Clinical features | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosisCite this page: Stuart L. Intranodal palisaded myofibroblastoma . PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueintranodalpalisaded.html. Accessed June 9th, 2023.
Definition / general
- Benign lymph node tumor composed of myoid or myofibroblastic spindle cells, with focal palisading and so-called "amianthoid" fibers
- Distinctly resembles schwannoma
Terminology
- Also called intranodal hemorrhagic spindle cell tumor with amianthoid fibers
- Formerly called intranodal schwannoma
- Amianthoid: resembles amianthus, a type of asbestos with particularly fine fibers (see images below); although tumor fibers resemble amianthoid fibers, they are actually composed of normal thickness collagen rather than the thick collagen fibers comprising "true" amianthoid fibers (Arch Pathol Lab Med 2007;131:306)
- Initially described by Weiss et al (Am J Surg Pathol 1989;13:341) and Suster et al (Am J Surg Pathol 1989;13:347)
Images hosted on other servers:
Amianthoid
Epidemiology
- 2/3 male, 2/3 ages 45 - 55 years, no ethnic predisposition (Arch Pathol Lab Med 2007;131:306)
Sites
- Lymph nodes, usually inguinal (Arch Pathol Lab Med 2007;131:306)
Pathophysiology
- Not fully elucidated, but may be influenced by cyclin D1 overexpression (Arch Pathol Lab Med 2003;127:1040)
- May be due to viral oncogenesis (Diagn Pathol 2010;5:12)
Clinical features
- Painless, slow growing (Arch Pathol Lab Med 2007;131:306)
Prognostic factors
- Rare local recurrence (Arch Pathol Lab Med 1999;123:433)
- No distant metastasis reported
Case reports
- 62 year old man with supraclavicular mass (Univ Pittsburgh Case #121)
- 71 year old man with inguinal mass (Arch Pathol Lab Med 2003;127:1040)
Treatment
- Local excision is almost always curative
Gross description
- Well circumscribed, gray-white with hemorrhage and peripheral nodal tissue
Microscopic (histologic) description
5 key features:
- Spindle cell proliferation surrounded by hemorrhage and collagenous pseudocapsule; growing nodule compresses remaining nodal tissue
- Bland spindle cells with areas of nuclear palisading
- Intraparenchymal hemorrhage and red blood cell extravasation
- So-called amianthoid fibers
- Extra- and intracellular fuchsinophilic bodies (best seen with SMA stain, Arch Pathol Lab Med 2007;131:306)
Microscopic (histologic) images
Images hosted on other servers:
Various images
Amianthoid fibers composed of a
central vessel surrounded by a core
of collagen with peripheral spokes,
strongly stained by Van Gieson (elastin)
Cytology description
- Moderately cellular with benign appearing, dissociated, single spindle cells 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, cyclin D1 (Arch Pathol Lab Med 2003;127:1040, J Clin Pathol 1991;44:761), factor XIIIa (variable)
- So-called amianthoid fibers: elastic stains, trichrome, smooth muscle actin, collagen (type I is positive in center of fibers, type III is positive in periphery, Arch Pathol Lab Med 2007;131:306)
Electron microscopy description
- Rough endoplasmic reticulum cisternae
- Some smooth-muscle type myofilaments
- Subplasmalemmal densities, plasmalemmal caveolae, and external lamina at cell surface
- Lacks the fibronexus junctions typical of myofibroblasts
- So-called "amianthoid fibers" are actually collagen fibrils with typical diameter of 50 - 83 nm, compared to giant collagen fibrils typical of true amianthoid (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, usually metastasizes to lung
- Follicular dendritic cell sarcoma: nests or whorls of plump cells with scattered inflammatory cells, no prominent hemorrhage, no amianthoid fibers, CD21+, CD35+
- Kaposi sarcoma: curved fascicles of spindle cells with atypia and PAS+ hyaline globules, brisk mitotic activity, slit-like vessels with extravasated red blood cells, scattered plasma cells in infiltrate, no amianthoid fibers; HHV8+, FLI1+, CD34+, CD31+
- Sarcoma (metastatic to lymph node): more atypical and more mitotically active, most sarcomas do not present initially with lymph node metastases (although nodal metastasis may develop in patients with disseminated disease)
- Schwannoma: often biphasic, no amianthoid fibers, not nodal, S100+
- Spindle cell carcinoma (metastatic to lymph node): more atypical and more mitotically active, often keratin+, p63+
- Spindle cell melanoma (metastatic to lymph node): more atypical and more mitotically active, S100+
