Spindle Cell Sarcoma

SCS may develop virtually anywhere, with predilection sites of subtypes as follows:

• Fibrosarcoma: deep soft tissues of limbs, trunk, head and neck [6]
• Leiomyosarcoma: uterus and kidneys
• Synovial sarcoma: feet, knees, hands, or otherwise in close proximity to the joints of arms and legs
• Malignant peripheral nerve sheath tumor: limbs and trunk wall, less frequently observed in head and neck region [7]

SCS, not otherwise specified, is very rare and predilection sites can't be reported [8].

Depending on the site of tumor growth, SCS may or may not be palpable. If so, they are generally of firm consistency. SCS may exert local mass effects and ensuing symptoms may comprise edema, neurological deficits, gastrointestinal or urogenital complaints, pain and reduced motion ranges, among others. Of note, lesions are not necessarily painful [9].

Furthermore, patients suffering from SCS may experience non-specific constitutive symptoms like fatigue, fever, and weight loss.

Computed tomography scans or magnetic resonance imaging should be carried out to confirm the presence of a tumor and to assess its extension. In images obtained by means of either technique, SCS typically appear as heterogeneous masses with pronounced contrast enhancement [9]. Invasive growth behavior may be observed.

For tumor grading, representative tissue samples should be obtained. An incisional biopsy should be performed if feasible [10]. Otherwise, core needle biopsies are preferred over fine-needle aspirations. As per definition, spindle-shaped cells dominate the histological picture. These cells have an extended body and tapered ends and may contain elongated nuclei. With regards to cell morphology, distinct degrees of pleomorphism may be observed. Necrotic foci may be present. The share of actively proliferating cells, expressed as the mitotic index, should be determined.

Spindle cell sarcoma (SCS) is a malignant neoplasm of mesenchymal origin. The term is used somewhat inconsistently and may refer to not otherwise specified soft tissue tumors (according to "Pathology and Genetics of Tumors of Soft Tissue and Bone" as proposed by the World Health Organization Classification of Tumors [1]), or to any of the following entities:

• Malignant fibrous histiocytoma
• Fibrosarcoma
• Leiomyosarcoma
• Synovial sarcoma
• Malignant peripheral nerve sheath tumor

Although the respective hypothesis is not yet universally accepted, recent evidence implies mesenchymal stem cells to undergo malignant transformation and to form undifferentiated SCS [2]. With regards to the given list, the term malignant fibrous histiocytoma should be avoided since these tumors are no longer assumed to be of histiocytic lineage [3]. The remainder of enumerated tumors originate from connective tissue or smooth musculature, or from as-of-yet undefined tissues. In any case, "spindle" refers to the morphology of tumor cells as observed upon in histopathological analysis.

A considerable share of SCS corresponds to radiation-associated sarcomas [4]. Genetic factors play a major role in SCS etiology; patients suffering from the Li-Fraumeni syndrome, neurofibromatosis type I, Rothmund Thomson syndrome, and Werner syndrome are predisposed for sarcomas [5].

SCS are likely to invade neighboring tissues and metastasize into distant organ systems, e.g., into lungs, liver, and kidneys. While surgery is mostly indicated to treat SCS, chemotherapy and irradiation may also be used in some cases where surgery cannot be done. However, the patient's prognosis worsens rapidly with increasing tumor stages.

1. Fletcher C, Bridge J, Hogendoorn P, Mertens F. World Health Organization classification of tumours of soft tissue and bone: pathology and genetics of tumours of soft tissue and bone. 4 ed. Lyon, France: IARC Press; 2013.
2. Rodriguez R, Rubio R, Menendez P. Modeling sarcomagenesis using multipotent mesenchymal stem cells. Cell Res. 2012; 22(1):62-77.
3. Al-Agha OM, Igbokwe AA. Malignant fibrous histiocytoma: between the past and the present. Arch Pathol Lab Med. 2008; 132(6):1030-1035.
4. Fletcher CD. The evolving classification of soft tissue tumours - an update based on the new 2013 WHO classification. Histopathology. 2014; 64(1):2-11.
5. Fernebro J, Bladstrom A, Rydholm A, et al. Increased risk of malignancies in a population-based study of 818 soft-tissue sarcoma patients. Br J Cancer. 2006; 95(8):986-990.
6. Folpe AL. Fibrosarcoma: a review and update. Histopathology. 2014; 64(1):12-25.
7. Le Guellec S, Decouvelaere AV, Filleron T, et al. Malignant Peripheral Nerve Sheath Tumor Is a Challenging Diagnosis: A Systematic Pathology Review, Immunohistochemistry, and Molecular Analysis in 160 Patients From the French Sarcoma Group Database. Am J Surg Pathol. 2016; 40(7):896-908.
8. Toro JR, Travis LB, Wu HJ, Zhu K, Fletcher CD, Devesa SS. Incidence patterns of soft tissue sarcomas, regardless of primary site, in the surveillance, epidemiology and end results program, 1978-2001: An analysis of 26,758 cases. Int J Cancer. 2006; 119(12):2922-2930.
9. Nissim L, Mackstaller L, Hooten J, Motamedi K, Graham A, Taljanovic M. Spindle-cell sarcoma of the popliteal fossa mimicking a benign vascular lesion. Radiol Case Rep. 2010; 5(1):340.
10. Coindre JM. Grading of soft tissue sarcomas: review and update. Arch Pathol Lab Med. 2006; 130(10):1448-1453.