Breast
Other benign tumors
Benign stromal spindle cell tumors
Author: Monika Roychowdhury, M.D.
Topic Completed: 1 September 2015
Minor changes: 17 February 2021
Copyright: 2002-2019, PathologyOutlines.com, Inc.
PubMed Search: Benign stromal spindle cell tumors breast
Table of Contents
Definition / general | Terminology | Pathophysiology | Etiology | Clinical features | Case reports | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Differential diagnosisCite this page: Roychowdhury M. Benign stromal spindle cell tumors. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastbssct.html. Accessed October 21st, 2021.
Definition / general
- Tumors composed of benign spindle cells, with variable lines of differentiation
- First described by Toker (Cancer 1981;48:1615)
- Terminology used in Tavassoli: Tavassoli: Tumors of the Mammary Gland, AFIP Atlas of Tumor Pathology, Series 4, First Edition, 2009
Terminology
- Myofibroblastoma: BSSCT with predominant myofibroblastic differentiation
- Spindle cell lipoma: BSSCT with predominant adipocytic component
- Solitary fibrous tumor / hemangiopericytoma: BSSCT with predominant fibroblastic elements
Pathophysiology
- Represent variations of the same tumor entity, likely arising from the uncommitted vimentin+ / CD34+ fibroblasts of the mammary stroma, capable of multidirectional mesenchymal differentiation (Pathol Res Pract 2001;197:453)
- Can be subtyped into 4 main groups based on morphology and immunohistochemistry:
- Fibroblastic
- Myofibroblastic
- Fibrohistiocytic
- Mixed forms (Pathol Res Pract 2001;197:453)
Etiology
- Mesenchymal tumors composed of cells capable of various lines of differentiation, including fibroblasts, myofibroblasts, adipocytes and smooth muscle cells
- Histologic variations reflect the features seen in the four types of myofibroblasts:
- V: vimentin
- VA: vimentin and actin
- VAD: vimentin, actin and desmin
- VADM: vimentin, actin, desmin and myosin (Am J Surg Pathol 1998;22:141)
Clinical features
- Benign
Case reports
- Breast spindle cell tumours (Diagn Pathol 2006;1:13)
Gross description
- Solid, well circumscribed, noncystic breast mass
Microscopic (histologic) description
- Myofibroblastoma:
- Spindle cells, hyalinized collagen bundles and adipocytes
- Can have cellular pleomorphism
- Based on the ratio of components and pleomorphism, subclassified as classic, collagenized, epithelioid, cellular, lipomatous and variants resembling solitary fibrous tumor
- Spindle cell lipoma: spindle cells intermingled with adipocytes and collagen bundles
- Hemangiopericytoma:
- Closely packed, spindle shaped cells with indistinct cell margins arranged around thin walled irregular branching vessels
- The latter may have a 'staghorn' configuration
Microscopic (histologic) images
Images hosted on other servers:
Spindle cell carcinoma, CD10, S100, SMA
Myofibroblastoma, CD34, S100
Spindle cell lipoma, CD34
Leiomyosarcoma, desmin
Myoepithelial carcinoma, S100, CD10
Cytology description
- Myofibroblastoma: cellular specimen with bipolar spindle cells, bland nuclei with grooves
- Nonspecific cytologic features for spindle cell lipoma and hemangiopericytoma
Positive stains
- bcl2, CD10, CD99, smooth muscle actin
- Spindle cell lipoma: vimentin, CD34
- Myofibroblastoma: vimentin, CD34, actin, desmin
- Hemangiopericytoma: vimentin, actin, CD31, CD34, factor VIII
Differential diagnosis
- Myoepithelial carcinoma, spindle cell subtype: nuclear atypia, mitotic figures, necrosis, keratin+
- Myofibrosarcoma: mitotic figures and necrosis
- Nodular fasciitis: spindle to round plump cells with frequent mitoses, myxoid tissue-culture like stroma, inflammatory lymphocytic component and extravasated RBCs
- Desmin negative, positive for actin and focal CD34
- Sarcomatoid carcinoma: may have hemangiopericytoma-like vascular pattern but also nuclear atypia, frequent and atypical mitotic figures, necrosis
- Spindle cell myoepithelioma: no collagen bundles, keratin+
