Uncommon malignancies: case 1. Low-grade myofibroblastic sarcoma of the breast

Myofibrosarcoma of Maxilla - Case Report and Review of Literature

Myofibrosarcoma is a distinct mesenchymal malignancy which commonly occurs in head and neck region. It has a high tendency for local recurrence and distant metastasis. 39-year-old male presented with epistaxis, nasal obstruction and left sided complete loss of vision. He underwent functional endoscopic sinus surgery and guided biopsy. MRI scan showed a lesion epicentred in the left maxillary sinus, superiorly extending into the orbit. He underwent Class 4b maxillectomy with neck dissection, tracheostomy and free flap reconstruction. Histopathological examination yielded final diagnosis as myofibrosarcoma of maxilla. The patient was planned for adjuvant radiotherapy and has been disease free for 3 years.

Myofibroblastic sarcoma in breast: a case report and literature review

Myofibroblastic sarcoma is a malignancy in which myofibroblasts are the main component, with a very low incidence. In this study, we report a case of low-grade myofibroblastic sarcoma (LGMS) in the breast. After the diagnosis of LGMS, the patient received a mastectomy. The patient showed no relapse or progression during the follow-up time of 3 months following the operation. LGMS in the breast is extremely rare, and the limited experience with its diagnosis and treatment brings obstacles to doctors. Therefore, this report summarizes the preoperative diagnosis, treatment, and prognosis of breast LGMS through a literature review.

A Systematic Review and Illustrative Case Presentation of Low-Grade Myofibroblastic Sarcoma (LGMS) of the Extremities

INTRODUCTION

Low-grade myofibroblastic sarcoma (LGMS) is a rare tumor entity which occurs in the subcutaneous and deep soft tissues; it is less common in the bone with a predilection for the extremities and the head and neck region. As confirming the diagnosis is difficult and treatment strategies are not standardized, we aimed to identify patient and tumor characteristics, and to summarize treatment strategies and their clinical outcomes to guide surgeons.

METHODS

Included were full articles reporting patients with histology of LGMS in the extremities, excluding tumors of the trunk. All patients underwent surgery but with different extend, from marginal to wide resection. Included studies should inform about local recurrence, metastasis, or evidence of disease, depending on the surgical treatment. We conducted a structured search using MEDLINE (via PubMed), Web of Science, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies on low-grade myofibroblastic sarcoma of the extremities. Study designs like randomized controlled trials, systematic reviews, prospective trials, retrospective studies, and case reports were included. Prospective studies and comparative studies were not available at all. Therefore, meta-analysis was not possible and statistical analysis was purely descriptive.

RESULTS

Of the 789 studies identified from our initial search, 17 studies including 59 cases reported LGMS of the extremities with the surgical treatment and clinical outcome and were therefore analyzed. In addition, we present the rare case and surgical management of a 28-year-old male patient with residual LGMS of the thumb after an initial incomplete resection. The current literature suggests that a wide excision with R0 margins should be considered the standard treatment for LGMS. In cases where surgery leads to significant functional impairment, individual options like free tissue transfer from a donor site have to be considered. Therefore, we also present an illustrative case. For all selected case series and case reports, a high risk of confounding, selection bias, information bias, and reporting bias must be anticipated. Nevertheless, this systematic review provides a comprehensive overview on surgical treatment and clinical outcomes in LGMS surgery of the extremities.

Low-grade myofibroblastic sarcoma of the proximal femur: A case report and literature review

RATIONAL

Low-grade myofibroblastic sarcoma (LGMS) is an atypical type of tumor composed of myofibroblasts. LGMS in the femoral head neck junction is extremely rare and no case treated by hip arthroscopy was reported.

PATIENT CONCERNS

We reported a case of LGMS in the femoral head neck junction treated by hip arthroscopy. A 30-year-old female was admitted to our hospital with discomfort and pain after left hip sprained one year prior. Physical examination revealed swelling of the left hip and magnetic resonance images showed a soft tissue mass in the femoral head neck junction.

DIAGNOSIS

Via microscopy of pathological specimens, spindle cell proliferative lesions, atypia of some cells, and mitotic figures/pathological mitotic figures of some cells were observed. Immunohistochemistry revealed positive for smooth muscle actin, focally positive for CD34 and CD68, while negative for S-100, desmin, and anaplastic lymphoma kinase. The imaging, histomorphological and immunohistochemical features suggested a final diagnosis of LGMS of the proximal femur.

INTERVENTIONS

This patient underwent hip arthroscopy for excision of the soft tissue mass.

OUTCOMES

The clinical and imaging follow-up at 6 months postoperatively showed that surgery had achieved good clinical outcomes.

LESSONS

To the best of our knowledge, this is the first case report of LGMS in the femoral head neck junction treated by hip arthroscopy. Beyond the present case, other 120 cases from 58 literatures (1998-2022) are reviewed and discussed. The age of LGMS patients ranged from 11 months to 77 years and the male-to-female ratio was approximately 1.28:1. The location distribution of previously reported LGMS cases and the present case was as follows: Head&neck (45.90%), trunk (30.33%), and extremity (23.77%). Hip arthroscopic excision of LGMS may achieve relatively good clinical outcomes.

Giant chondroid lipoma of the breast: A case report and literature review

Chondroid lipoma is a rare benign lesion affecting the breast, in which the diagnosis of malignancy is difficult to be excluded during preoperative studies. In this respect, a correct histopathological diagnosis is mandatory in order to avoid overdiagnosis and subsequently overtreatment. In the present study, the case of a 61-year-old patient who self-referred for the development of a large tumor at the level of the left breast is reported. Biopsy raised the suspicion of a chondroid lipoma; thus, the patient was submitted to conservative surgery. The lesion was completely excised by performing a total mastectomy. The histopathological studies confirmed the presence of chondroid lipoma, with no signs of malignant transformation. At the 24-month follow-up interval no signs of recurrence were detected. In conclusion, although it may reach significant dimensions, giant chondroid lipoma of the breast is a benign lesion that may benefit from conservative treatment and does not recur.

Low-grade myofibroblastic sarcoma of the levator scapulae muscle: a case report and literature review

BACKGROUND

Low-grade myofibroblastic sarcoma (LGMS) is described as a distinct atypical myofibroblastic tumor often with fibromatosis-like features and predilection for the head and neck, especially the oral cavity and larynx. LGMS arising in the levator scapulae muscle is extremely rare.

CASE PRESENTATION

A 69-year-old woman was admitted to our hospital because she noticed a hard mass in her left neck six months prior. Magnetic resonance images (MRI) showed a soft tissue tumor of the left levator scapulae muscle. A core needle biopsy showed cellular fascicles or a storiform growth pattern of spindle-shaped tumor cells with minimally atypia. Immunohistochemistry revealed focally positive for α-smooth muscle actin (α-SMA), negative for S-100, and a low-grade spindle cell sarcoma was suspected. Following a biopsy, the tumor was resected with a wide surgical margin. Immunohistochemical staining was a positive for vimentin and α-SMA and negative for desmin, CD34, nuclear β-catenin, and h-caldesmon. LGMS diagnosis was determined based on the histopathological findings. The patient was alive with no evidence of disease eight years after the surgery.

CONCLUSIONS

To the best of our knowledge, this is the first case report of LGMS arising in the levator scapulae muscle. In addition to the case report, 48 reports with 103 LGMS cases are reviewed and discussed. In previous reports of LGMS, there were 43 females and 60 males, with a mean age of 43.0 years (range, 2-75). There were 13 (12.6%) patients aged < 18 years, 67 (65.1%) patients aged 18 to 59 years, and 23 (22.3%) patients aged ≥60 years. The average tumor size was 4.4 cm (range: 0.4-22.0). The commonest sites of LGMS was the tongue. Tumor growth patterns were evaluated in 52 cases, and 44 cases (84.6%) showed infiltrative growth patterns. Local recurrence was 26.7%, and distant metastasis was 4.4%. Because of the locally aggressive feature, it is important to diagnose LGMS with biopsy and to excise the tumor with an adequately wide margin.

Practical approach to diagnosis of bland-looking spindle cell lesions of the breast

The diagnosis of bland-looking spindle cell lesions of the breast is often challenging because there is a close morphological and immunohistochemical overlap among the different entities. The present review will discuss reactive spindle cell nodule/exuberant scar, nodular fasciitis, inflammatory pseudotumor, myofibroblastoma (classic type), lipomatous myofibroblastoma, palisaded myofibroblastoma, benign fibroblastic spindle cell tumor, spindle cell lipoma, fibroma, leiomyoma, solitary fibrous tumor, myxoma, schwannoma/neurofibroma, desmoid-type fibromatosis, dermatofibrosarcoma protuberans, low-grade fibromatosis-like spindle cell carcinoma, inflammatory myofibroblastic tumor and low-grade myofibroblastic sarcoma arising in the breast parenchyma. The pathologist should be aware of each single lesion to achieve a correct diagnosis to ensure patient a correct prognostic information and therapy. Accordingly representative illustrations and morphological/immunohistochemical diagnostic clues will be provided.

Myofibroblastic sarcoma of the breast. Report of a case induced by radiotherapys

Myofibroblastic sarcoma (MFS) is an uncommon tumor rarely located in the breast. Ionizing radiation is a carcinogen capable of inducing sarcomas through DNA damage. A 42-year-old woman was diagnosed with synchronous bilateral breast infiltrating ductal carcinoma with axillary lymph node metastases on the left side. After modified left radical mastectomy and simple right mastectomy, she underwent postoperative radiation with a total volume dose of 50 Gy that included the thoracic wall and the left axillary-supraclavicular region. After a latency period of 6 years and 4 months, the patient developed an MFS in the area of radiation (mammary upper outer quadrant). To our knowledge, only 11 cases of MFS have been previously published in the breast. The study of the 12 cases including the present one revealed that the ages of the patients ranged from 42 to 86 years (mean 60.3 years). There was a clear difference concerning sex (M:F, 1:5). The average duration of the lesion varied from 1 week to 8 months (mean 3.3 months). The size ranged from 2.2 to 22 cm (average 5.1 cm). The tumors showed frequent mitosis and areas of necrosis. The percentage of recurrences, metastasis, and death due to the tumor was 27.3%, 36.4%, and 27.3% respectively. MFS cases differ from those affecting extramammary regions. They are more common in females and show a greater degree of aggressiveness. Correct diagnosis of mammary MFS requires morphological and immunohistochemical study. We present for the first time a case of MFS of the breast induced by radiotherapy.

Low-grade Myofibroblastic sarcoma: clinical and imaging findings

Background

Low-grade myofibroblastic sarcoma (LGMS) is a rare type of tumor. Previous research has paid much attention to reporting pathological analyses of LGMS. However, only few systematic clinical and/or radiological studies have been conducted.

Methods

This study recruited 14 cases (8 males and 6 females) of LGMS. X-ray or computer tomography (CT) scan were performed on 11 cases. MRI was performed on 5 cases.

Results

X-Ray and CT scan: Five cases developed LGMS in bones, including 3 cases in the distal femur, 1 in the right shoulder blade, and another 1 in the right inferior ramus. Massive infiltrative and vermiform bone destruction with poorly-circumscribed lesion margins and partial soft tissue masses were observed. The other 9 cases were developed in soft tissues. Out of them, 4 cases presented slightly irregular hyper- or lower-density masses with poorly-circumscribed margins. 2 cases presented massive calcification and ossification. Significant enhancement was observed in 1 case, while no obvious enhancement was seen in the other 2 cases.

MRI: MR images of 5 cases revealed homogeneous iso- or hyper-signal intensity on T1WI and homogeneous or heterogeneous hyper-signal intensity on T2WI. Enhanced MRI revealed homogeneous enhancement in 2 cases and rim enhancement in 1 case.

Conclusions

Our findings show that LGMS is characterized by invasiveness, metastases and calcification. Different radiological tools should be employed to make an accurate diagnosis.

Differential Diagnosis of Benign Spindle Cell Lesions

Spindle cell lesions of the breast cover a wide spectrum of diseases ranging from reactive tumor-like lesions to high-grade malignant tumors. The recognition of the benign spindle cell tumor-like lesions (nodular fasciitis; reactive spindle cell nodule after biopsy, inflammatory pseudotumor/inflammatory myofibroblastic tumor; fascicular variant of pseudoangiomatous stromal hyperplasia) and tumors (myofibroblastoma, benign fibroblastic spindle cell tumor, leiomyoma, schwannoma, spindle cell lipoma, solitary fibrous tumor, myxoma) is crucial to avoid confusion with morphologically similar but more aggressive bland-appearing spindle cell tumors, such as desmoid-type fibromatosis, low-grade (fibromatosis-like) spindle cell carcinoma, low-grade fibrosarcoma/myofibroblastic sarcoma and dermatofibrosarcoma protuberans.

Low-grade myofibroblastic sarcoma of the orbit: A case report and literature review

RATIONALE

Low-grade myofibroblastic sarcoma (LGMS) is a malignant lesion composed of myofibroblasts. It is an uncommon tumor of unknown etiology that mainly develops in the bone or soft tissue and is most often reported in the head and neck, particularly in the tongue and oral cavity.

PATIENT CONCERNS

A 2-year-old girl, previously well and with no significant medical history or family history of other diseases, presented with a 2-week painless swelling of the right orbit.

DIAGNOSES

Preoperative computed tomography (CT) revealed a large homogeneous enhanced mass, 21 × 13 mm in size, located on lateral wall of the right orbit with bone absorption. The mass was resected and histopathological examination revealed LGMS of the orbit.

INTERVENTIONS

On May 2016, she underwent surgery without the additional postoperative treatment.

OUTCOMES

The patient's postoperative course was uneventful, and was discharged on the 6th day after surgery. During a year follow-up period, there was no recurrence of the postoperative CT. The patient and her family were satisfied with the result of the surgery.

LESSONS

Based on clinical characteristics and postoperative CT, we considered the mass may be a benign tumor. We completely resected along the capsule without an extensive surgical margin. However, postoperative histopathology diagnose LGMS, which shows a strong potential for local recurrence and vascular invasion. So we should close observation of the patient's symptoms and sign. If the tumor has invaded adjacent tissues, we will use adjuvant chemotherapy or radiotherapy.

Myofibroblastic, fibroblastic and myoid lesions of the breast

Myofibroblastic, fibroblastic and/or myoid lesions are rare in the breast but comprise the majority of mammary mesenchymal spindle cell lesions. Whereas most have similar features to their counterparts at extramammary sites, pseudoangiomatous stromal hyperplasia is considered a breast-specific myofibroblastic proliferation on the same spectrum as myofibroblastoma. Other lesions with myofibroblastic/fibroblastic differentiation include fibromatosis and nodular fasciitis, as well as more aggressive tumors such as the rarely reported myofibrosarcoma, inflammatory myofibroblastic tumor and fibrosarcoma. Lesions with myoid differentiation include benign leiomyoma, myoid hamartoma and leiomyomatous myofibroblastoma, but primary leiomyosarcoma and rhabdomyosarcoma may also rarely arise in the breast. Furthermore, fibroepithelial lesions and metaplastic carcinomas can demonstrate myoid metaplasia. Diagnosis can be challenging, particularly on core biopsy, but benign lesions with or without recurrence potential must be distinguished from more aggressive tumors, especially metaplastic carcinoma and phyllodes tumors. This article will review lesions with myofibroblastic, fibroblastic and myoid differentiation in the breast, with special emphasis on differential diagnosis.

Indolent growth of low-grade myofibroblastic sarcoma of the cheek mimics benign lesions: A case report and literature review

Low-grade myofibroblastic sarcoma (LGMS) is a neoplasm of the soft tissue characterized by myofibroblastic differentiation. This type of tumor has been observed in various sites in the whole body, but frequently occurs in the head and neck region. It typically presents as a slow-growing painless mass, which is often mistaken for a benign lesion due to its indolent growth; however, LGMS is a malignant neoplasm. In the present study, a 43-year-old female presented with a 14-mm LGMS lesion in the buccal subcutaneous tissues of the buccinator muscle. The patient had initially noticed the lesion 2-months prior to presenting at the hospital. Following biopsy, the tumor was surgically resected and no recurrence or metastasis was observed during a follow-up time of 2 years. To the best of our knowledge, this case is the first report of LGMS located in the buccal subcutaneous tissue of the buccinator muscle. The present study a literature review of 55 cases of this tumor type in the head and neck region was conducted, revealing that the indolent growth of these lesions may contribute to a delay in diagnosis. The average time between the onset of clinical symptoms and hospital admission is 3.9 months, and this form of tumor is frequently misdiagnosed as a benign lesion. Therefore, the present study suggests that an incisional biopsy may be performed to rule out LGMS when clinicians encounter patients with the aforementioned indolent lesions anywhere in the body. In addition, the avoidance of radiotherapy is recommended following resection of the LGMS tumor, as it may induce LGMS recurrence.

Low-grade myofibroblastic sarcoma arising in fibroadenoma of the breast-A case report

BACKGROUND

Myofibroblastic sarcoma or myofibrosarcoma is a malignant tumor of myofibroblasts and known to develop rarely in the breast, but its underlying lesion and tumor cell origin have never been reported yet.

CASE PRESENTATION

A 61-year-old female presented with a gradually growing breast mass with well-demarcated ovoid nodular shape. The tumor was histologically characterized by fascicular-growing spindle cell proliferation with large areas of hyalinized fibrosis and focally ductal epithelial remnants embedded in myxoid stroma, mimicking a fibroadenomatous lesion. It had frequent mitoses of 5-16/10 high-power fields, hemorrhagic necrosis, and focally pericapsular invasion. The spindle cells were diffusely immunoreactive for fibronectin, smooth muscle actin, and calponin, which suggest a myofibroblastic origin. Multiple irregularly thickened vessels with medial or pericytic cell proliferation were found to be merged with the intrinsic tumor cells. The tumor could be diagnosed low-grade myofibroblastic sarcoma arising in an old fibroadenoma.

CONCLUSION

We report a case of a low-grade mammary myofibrosarcoma that showed a background lesion of fibroadenoma first in the worldwide literature and suggest the pericytes or medial muscle cells of the intratumoral vessels as the cell origin of the myofibroblastic sarcoma.

Inflammatory Myofibroblastic Tumor of the Breast Coexisting with Pseudoangiomatous Stromal Hyperplasia

Inflammatory myofibroblastic tumors (IMTs) are uncommon breast lesions that consist of spindle cells accompanied by plasma cell-rich inflammatory infiltration, which may mimic breast cancer clinico-radiologically. A woman aged 38 years with a breast mass was referred to our general surgery clinic. The physical examination revealed a mass with irregular borders in the upper outer quadrant of the left breast. In mammography, the lesion was 15 mm in diameter with a spheric form and high density. Ultrasonographically, the mass was solid, heterogeneous, and hypoechoic with posterior enhancement. Histopathologic examination of a core needle biopsy revealed a proliferation of spindle cells with eosinophilic cytoplasm and mild nuclear atypia, which showed negative immunostaining for pancytokeratin, HMWCK, CAM5.2, p63, CD34, β-catenin, and ALK but diffuse positivity for smooth muscle alpha (SMA). The lesion was reported as a "spindle cell lesion" and excision with clear margins was recommended. In the lumpectomy specimen, the lesion consisted of spindle cells that formed fascicles and infiltrated the surrounding breast parenchyma. Lymphocytes and plasmocytes scattered among spindle cells were noted. Necrosis, increased mitotic activity, nuclear pleomorphism and hyperchromasia were not detected. Immunohistochemical findings were the same in the core needle biopsy. The Ki-67 proliferation index was below 5%. With these findings, differential diagnoses were ruled out and the tumor was reported as IMT. In close proximity to this lesion, areas of columnar cell lesion with atypia and surrounding pseudoangiomatous stromal hyperplasia were seen. Patient has a follow-up of 16 months without recurrence.

Low-grade myofibroblastic sarcomas of the maxilla

Low-grade myofibroblastic sarcoma (LGMS) is a distinct mesenchymal myofibroblastic malignancy. The tumor may occur at a variety of sites, but is particularly associated with the head and neck. Of the two maxillary sarcomas that were analyzed in the present study, one was misdiagnosed as an inflammatory myofibroblastic tumor during pre-operative excision biopsy, and later presented with a different immunophenotype upon recurrence. Representative paraffin blocks from formalin-fixed tissues were selected from each patient and designated as case 1 and case 2. Immunohistochemical studies were performed on 3-μm thick sections using primary antibodies against α-smooth muscle actin (α-SMA), muscle-specific actin (MSA), desmin, vimentin, calponin, h-caldesmon, fibronectin, cytokeratin, cluster of differentiation 34 (CD34), S-100 protein, anaplastic lymphoma kinase (ALK), epithelial membrane antigen (EMA) and Ki-67. Immunohistochemistry was performed using the streptavidin-biotin-peroxidase complex method. The tumor cells from the two maxillary LGMSs, including the recurrent lesion, were positive for vimentin and fibronectin, and negative for S-100 protein, CD34, EMA, h-caldesmon, ALK, MSA and calponin. The tumor cells from case 1 demonstrated positive staining for α-SMA protein and negative staining for desmin. By contrast, the tumor cells from the primary lesion in case 2 presented with negative staining for α-SMA and positive staining for desmin, while the cells of the recurrent lesion were α-SMA-positive and desmin-negative. The present study concluded that cases of LGMS with immunoprofile alterations are predictive of relatively poor prognoses.

Retrospective study and immunohistochemical analysis of canine mammary sarcomas

BACKGROUND

Canine mammary sarcomas (CMSs) are rarely diagnosed in female dogs, which explains the scarcity of immunohistochemical findings concerning those tumors. This paper presents the results of a retrospective study into CMSs and discusses the clinical features of the analyzed tumors, the expression of intermediate filaments CK, Vim, Des and α-SMA, and the expression of p63, Ki67, ERα, PR and p53 protein.

RESULTS

Four percent of all canine mammary tumors (CMTs) were classified as CMSs, and they represented 5.1% of malignant CMTs. The mean age at diagnosis was 11.1 ± 2.8 years. Large breed dogs were more frequently affected (38.7%). The majority of observed CMSs were fibrosarcomas (2.1%). All CMSs expressed vimentin, and higher levels of vimentin expression were noted in fibrosarcomas and osteosarcomas. Ki67 expression was significantly correlated with the grade of CMS.

CONCLUSIONS

Our results revealed that CMSs form a heterogeneous group, therefore, immunohistochemical examinations could support differential and final diagnosis. Although this study analyzed a limited number of samples, the reported results can expand our knowledge about CMSs. Further work is required in this field.

Myofibroblastoma breast with unusual morphological features. Cytohistopathogical diagnostic pitfalls and role of immunohistochemistry-review of literature

Myofibroblastoma (MFB) is a rare mesenchymal tumour, derived from mammary stromal fibro-myofibroblasts, with diverse biological and morphological behaviour. Large and cellular myofibroblastomas, especially those with epitheliod like cells, can mimic various spindle cell lesions and metaplastic carcinomas, thus posing diagnostic challenge. A 50-year woman presented with slow growing, painless lump in the left breast. Fine Needle Aspiration (FNA) smears showed predominant atypical spindle cell population, pleomorphic epithelial like cells and giant cells. Cytodiagnosis of atypical spindle cell lesion with the possibility of metaplastic carcinoma was suggested. Histopathological examination showed fascicles of spindle cell population admixed with epithelial like cells, atypical cells and tumour giant cells, thus raising differential diagnosis of metaplastic carcinoma, low grade spindle cell sarcoma and myofibroblastic tumour. Lymph nodes were negative for metastatic deposits. Immunohistochemistry revealed variable coexpression of markers for vimentin, fibronectin, CD34, SMA (smooth muscle actin), but negative expression for , S-100, CD99, CK7 (cytokeratin 7), HMWK (high molecular weight keratin), ER (oestrogen receptor) and PR(progesterone receptors). Diagnosis of cellular myofibroblastoma with mixed unusual morphological features was defined, based on both histological and immunohistochemical features. MFB may cause a potential diagnostic pitfall while interpreting FNA and histopathological sections due to its wide differential diagnosis. The distinction of MFB from its cytohistological mimics of malignancy is crucial to avoid unnecessary extensive procedures. The case report emphasizes the role of immunohistochemistry as gold standard in diagnosis of MFB. The case is also being presented because of its large size and rare mixed unusual morphological features.

Ultrastructurally confirmed myofibrosarcoma: a series of 10 new cases, with a discussion on diagnostic criteria

Some view ultrastructure as key to myofibrosarcoma diagnosis, whereas others argue that electron microscopy is too little used in contemporary practice to be considered an important diagnostic tool. These views are discussed in the context of 10 ultrastructurally confirmed cases of myofibrosarcoma, some occurring at rare sites such as skin and penis. Patient age ranged from 21 to 83 years, with a 6:4 male to female ratio. Size ranged from 2 to 7.5 cm and all had infiltrative margins. Histologically, all consisted of variably cellular fascicles of spindle cells with mild to moderately pleomorphic nuclei, small punctate nucleoli, and eosinophilic cytoplasm. All cases showed α-smooth muscle actin positivity and 2 showed very focal weak positivity for desmin. Ultrastructurally, the tumor cells contained rough endoplasmic reticulum, mainly peripheral smooth-muscle myofilaments, and fibronectin fibrils or fibronexus junctions at the cell surface. The most confident diagnosis of myofibrosarcoma is provided by ultrastructural examination. However, given the right histological appearance, use of a panel of antibodies that includes α-smooth muscle actin, desmin, and h-caldesmon, serves as an acceptable practical way of diagnosing myofibrosarcoma.

Giant malignant phyllodes tumor: a case report

We present a case of a 57-year-old woman with a giant malignant phyllodes tumor (PT) in her right breast, with maximum diameter of 20 cm. The core-needle and excisional biopsy specimens were diagnosed as suspicious for low-grade myofibroblastic sarcoma (LGMS). The subsequent total mastectomy with partial resection of the pectoral muscles showed predominance of stromal hypercellularity without an epithelial component. However, we diagnosed this as a malignant PT because focal areas showed a leaf-like pattern. In the case of large malignant PTs that exhibit stromal predominance, it can be difficult to distinguish between a pure sarcoma and malignant PT. It is important to thoroughly examine multiple sections from the view point of residual epithelial structure in morphological diagnosis.

Mammary myofibrosarcoma: case report and literature review

A case of myofibrosarcoma of breast is reported. A female patient aged 81 years presented with a mammary mass lesion. Histologically, the tumor consisted of neoplastic spindle cells arranged in fascicles and with variably cellularity and hyalinization. Immunohistochemical studies showed expression of vimentin, smooth-muscle actin, and Bcl-2, but not desmin, S-100, C-kit, or CD34. Proliferative index identified by Ki67 was approximately 30%. Electron microscopy revealed variable amount of rough endoplasmic reticulum, myofilaments, fibronexus junctions, and fibronectin fibrils. The histological, immunohistochemical, and ultrastructural features of this tumor were consistent with myofibrosarcoma. This case will be one of the very few cases of ultrastructurally confirmed mammary myofibrosarcoma reported in the literature and contributes to the recognition of this rare mammary malignant neoplasm. The literature on mammary myofibrosarcoma and its differential diagnosis is also reviewed.

Mammary Myofibroblastoma: A Tumor With a Wide Morphologic Spectrum

Context.—Myofibroblastoma (MFB) of the breast is an unusual benign tumor that belongs to the family of the “benign spindle cell tumors of the mammary stroma.” The name MFB reflects its cellular composition, comprising mainly stromal cells with fibromyofibroblastic and, less frequently, myoid differentiation. Since the original description, the morphologic spectrum of MFB has been expanded by the recognition of several unusual morphologic variants, such as the cellular, infiltrative, epithelioid, deciduoid-like, lipomatous, collagenized/fibrous, and myxoid variants.

Objective.—To review the literature on mammary MFB, discussing the main clinical, radiologic, and pathologic features helpful for diagnosis. Since MFB may show alarming morphologic features, which can lead to a misdiagnosis of malignancy, histologic figures of this tumor, including its more unusual variants, are provided to offer pathologists a practical approach to a correct diagnosis. Histogenesis and pathogenesis of this tumor are also proposed.

Data Sources.—Clinicopathologic data on MFB were extracted from all identified articles through PUB Medline– based research. Histologic figures have been taken from the personal archive of the author.

Conclusions.—The incidence of MFB diagnosis has increased in recent years, likely due to the mammographic screening. Accordingly, this unusual benign tumor may represent a potential diagnostic pitfall, especially when interpreting fine-needle aspiration and/or needle core biopsy. Pathologists should be aware of the wide morphologic spectrum exhibited by MFB to avoid a misdiagnosis of malignancy.