Low Grade Myofibroblastic Sarcoma of the Scalp
Year: 2025
Type: article
Study design: Case Report
Abstract: Sir, Included in the WHO classification of bone and soft tissue tumors as a new disease entity in 2002, low grade myofibroblastic sarcoma (LGMS) is a distinct myofibroblastic malignancy with predilection for the head and neck region. It occurs predominantly in adult patients with slight male predominance.[1] The differential diagnosis of myofibroblastic lesions is very difficult and based mainly on careful examination of histopathological and immunohistochemical features. LGMS has a tendency for local recurrence and is associated with a low risk of metastatic spread.[2] As a general rule, surgical resection is the main means of treatment; wide excision of the tumor should be performed supplemented with postoperative radiotherapy and chemotherapy depending on the final diagnosis and prognosis. This is a case of 36-year-old man with a mass lesion growing in the front of scalp in midline for 1 year. The mass was 4 cm × 5 cm in dimension under the scalp, firm in consistency with no surface ulceration or growth. Computed tomography (CT) [Figure 1] and magnetic resonance imaging (MRI) scans revealed a well-defined heterogeneously enhancing mass causing destruction of underlying frontal bone and compression of superior sagittal sinus. Patient underwent wide local excision of the mass lesion with cranioplasty [Figures 2 and 3a and 3b]. Diagnosis was confirmed with histopathology and immunohistochemistry [Figure 4]. The patient is free after 1 year of excision without any recurrence. Review of literature of LGMS is discussed.Figure 1: Preoperative CT scan of the head, axial view showing a well-defined mass lesion over the frontal bone in midlineFigure 2: Intraoperative picture of the mass lesion: well-defined white to yellow, firm mass with erosion of the underlying frontal boneFigure 3: (a) Postoperative CT scan of the head, axial view: postoperative cranioplasty. (b) Postoperative CT scan of the head with 3D reconstruction: postoperative cranioplastyFigure 4: High power microscope view of histology: spindle cellsLGMS is a distinct atypical myofibroblastic tumor with fibromatosis-like features and has a predilection for the head and neck.[1] More than 80% of malignant tumors of the head-and-neck originate from squamous epithelium. Therefore, the incidence of mesenchymal tumors is low. Among them, myofibroblastic sarcomas are extremely rare.[2] Myofibroblasts have been recognized for over three decades, but the existence of sarcomas composed of myofibroblasts has become generally accepted recently.[3] Myofibroblasts were originally described and defined by Gabbiani et al.[4] by means of electron microscopy. Myofibroblasts are spindle mesenchymal cells sharing features of both muscular and fibroblastic cells and represent a connective tissue cell characterized by morphologic and functional properties intermediate between fibroblasts and smooth muscle cells. They are present in connective tissue and contribute to reparative and reactive conditions, such as granulation tissue, hypertrophic scars, myofibroblastoma, and even appear in the desmoplastic stroma of carcinoma.[5] In 1978, Vasudev et al.[6] first reported the pathological features of myofibroblastic sarcoma. Since then, only a few related case reports and series have been reported in the literature. In 1998, Mentzel et al.[7] using immunohistochemical and ultrastructural observations, confirmed this tumor in a series of patients and named it “low-grade myofibroblastic sarcoma.” In 2001, Montgomery et al.[8] reported on a group of similar cases, and further clarified the morphological diagnosis standard of this disease. In the 2002 WHO classification of soft tissue and bone tumor pathology and genetics, LGMS was for the first time classified as a distinct entity. However, although only LGMS is included in the WHO classification, moderate-to-high grade tumors have also been reported in the literature, especially in recent years.[1,2] The age of onset of myofibroblastic sarcoma has been reported to range from 6 to 75 years (mean age, 40 years), with a slight male predominance.[8] The case described here is that of a 360 year-old male. Myofibroblastic sarcoma is prone to occur in the soft tissues of the head and neck and in bone tissue, as well as in the limbs, chest wall, axillae, inguinal area, and abdominal/pelvic cavity. The tumors are mostly solitary, and rarely present as multiple masses. In most cases, patients complain of a painless swelling or an enlarging firm mass with pale surface; gradually developing over a period of 4 weeks to 72 months (mean, 13 months).[7,8] Although pain or related symptoms are rarely reported, this patient complained of mild tenderness. Histologically, LGMS is composed of slender spindle cells arranged in interlacing fascicles. LGMS have a mild to moderate amount of eosinophilic or amphophilic cytoplasm and fusiform nuclei and are usually characterized with mild nuclear pleomorphism and low mitotic rate (1–6/10 HPFs). Immunohistochemically, cells have a variable immunophenotype.[5,9,10] The markers include smooth muscle actin (SMA), desmin, muscle actin (HHF35), and calponin.[9] Most cells are positive for SMA, while fewer than half are positive for desmin. In contrast, LGMS does not stain for S-100 protein, laminin, epithelial markers (cytokeratin and epithelial membrane antigen), CD21, CD23, CD117, h-caldesmon, and anaplastic lymphoma kinase.[10] Myofibroblasts are similar to fibroblasts and smooth muscle cells in morphology and show overlapping features in terms of the immunophenotype; accordingly, they are easily misdiagnosed, and the differential diagnosis is, thus, especially important. Many other lesions should be considered including: fibromatosis, leiomyosarcoma, malignant fibrous histiocytoma, fibrosarcoma, malignant peripheral nerve sheath tumor, and inflammatory myofibroblastic tumor.[11,12] Although the treatment has not been clearly defined, an aggressive surgical resection with wide tumor-free margins, and, occasionally, radiotherapy or chemotherapy, is the preferred therapeutic option.[5,6,9,10] LGMS is, as the name suggests, a low-grade malignant tumor, which is prone to relapse but rarely metastasizes.[1,5,13] On the other hand, moderate-to-high grade myofibroblastic sarcoma is not only associated with frequent relapses but also with a high risk of metastasis.[1,5] Chiller et al.[14] reported that the recurrence rate of this tumor was 44–75%, and that the metastasis rate was as high as 44%; these rates were all higher in moderate-to-high grade cases, and there were even some mortality cases in their study. Therefore, recognition of myofibroblastic sarcoma and appropriate management with close follow-up is essential to prevent late recurrence or metastases. Table 1 summarizes reported cases of myofibroblastic sarcoma.Table 1: Summary reported cases with low-grade myofibroblastic sarcomaLGMS is a rare entity with a smaller number of cases reported in literature. It is a low-grade spindle cell sarcoma usually arising in the head and neck region in adult population with slight preponderance to males. Confirmation of diagnosis is based on histopathological findings and immunohistochemistry. Radical excision is the treatment of choice. Radiotherapy and chemotherapy are secondary line of treatment in case of recurrent tumors. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Source: Neurology India
Authors: P Bhaskar Naidu, Ravi Shekhar, Sudha Ram, K Selvakumar
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W4407798586