Myofibroblastoma of the breast: report of a case

Keloidal Collagen May Be Produced Directly by αSMA-positive Cells: Morphological Analysis and Protein Shotgun Analysis

Keloids are fibroproliferative lesions caused by abnormal dermal wound healing. Keloidal collagen (KC) is a pathognomic feature of keloids, but the mechanism by which it forms is unknown. This study aimed to evaluate the histopathology of KC and thereby gain clues into how it forms.

Methods

The cross-sectional study cohort consisted of a convenience series of patients with keloids who underwent surgical excision. Skin pieces (3 mm²) were collected from the keloid center and nearby control skin. Histopathology was conducted with light and electron microscopy and immunohistochemistry. KC composition was analyzed with protein shotgun analysis.

Results

Microscopic analyses revealed the ubiquitous close association between KC and αSMA-positive spindle-shaped cells that closely resembled myofibroblasts. Neither KC nor the spindle-shaped cells were observed in the control tissues. Compared with control skin, the collagen fibers in the KC were overall thinner, their diameter varied more, and their spacing was irregular. These features were particularly pronounced in the collagens in the vicinity of the spindle-shaped cells. Protein shotgun analysis did not reveal a specific collagen in KC but showed abnormally high abundance of collagens I, III, VI, XII, and XIV.

Conclusions

These findings suggest that KC may be produced directly by myofibroblasts rather than simply being denatured collagen fibers. Because collagens VI and XII associate with myofibroblast differentiation, and collagen XIV associates with local mechanical stress, these collagens may reflect, and perhaps contribute to, the keloid-specific local conditions that lead to the formation of KC.

Mammary Myofibroblastoma: Report of a Case and Review of the Literature

Mammary myofibroblastoma is a benign mesenchymal tumor composed of fibroblasts, myofibroblasts, and a variable number of adipocytes. Mammary myofibroblastoma usually occurs in men of older age and is less common in postmenopausal women. It may also happen in extramammary sites along the milk line. In this instance, it is referred to as mammary-type myofibroblastoma. Rarely multifocal and bilateral tumors have been described. Clinically and radiologically, it can be misinterpreted as a malignant tumor due to its rarity. Size usually does not exceed 3 cm. The diagnosis requires clinicopathological correlation with morphological and immunohistochemical evaluation, especially in limited biopsy specimens. We herewith describe a rare case of mammary myofibroblastoma in a 37-year-old female patient. We also review the literature focusing on the potential differential diagnostic issues and discuss this tumor's ultrastructural and cytogenetic findings.

Myofibroblastoma of the breast: two case reports and literature review

Myofibroblastoma (MFB) is a relatively rare tumor of the breast parenchyma, which belongs to the family of the 'benign stromal tumor of the breast'. Two cases of MFB of the breast are described. Radiological imaging is nonspecific in MFB, and pathological examination of needle biopsy or surgically resected specimen is necessary for the diagnosis. Surgery is recommended and considered curative without additional treatment; however, patients should be followed-up.

Clinicopathological and radiological characterization of myofibroblastoma of breast: A single institutional case review

Myofibroblastoma is a rare type of benign myofibroblastic neoplasm in the breast. It is clinically presented as a well-circumscribed mass, usually small in size (usually less than 4.0 cm), and can mostly be cured by local excision. Rare cases of giant myofibroblastoma greater than 10 cm have been reported, but also follow a benign clinical course. Histologically, breast myofibroblastoma is featured by bland fascicles of spindle cells intermixed with thick hyalinized collagen bundles. Mast cells are frequently found within the stroma. However, a wide spectrum of morphological variants can occur in myofibroblatoma, making its diagnosis challenging sometimes. Differential diagnosis of myofibroblastoma with other spindle cell lesions in the breast, either benign or malignant, is also important in practice. In this study, we collected 15 cases of breast myofibroblastoma diagnosed in our institution during a 20 year period. The sizes of these cases range from 0.4 cm to 35.2 cm (mean is 3.7 cm). To our knowledge, the case of giant breast myofibroblastoma we presented here is the largest one reported to date. The histological examination of the cases show great morphological variations. Besides the classical type, features of cellular, collagenized, palisading, epithelioid, myxoid, myoid, solitary fibrous tumor-like are also identified in the case series. Immunohistochemical staining patterns as well as clinical features of the cases are also summarized and compared. All cases in this study show no recurrence on follow-up. In addition, cases that are important differential diagnosis for breast myofibroblastoma are also studied. Their key histological characteristics are compared with myofibroblastoma, and their immunohistochemical and molecular features are discussed.

Myofibroblastoma of the breast in postmenopausal women: Two case reports with imaging findings and review of the literature

Myofibroblastoma is a rare benign mesenchymal tumor of the breast, which tends to affect postmenopausal women and older men. It usually presents as a unilateral, well-circumscribed, firm, nontender, and freely mobile mass. We report two cases of myofibroblastoma in postmenopausal women with the imaging findings of mammography, ultrasonography, computed tomography, ¹⁸ F-Fluorodeoxyglucose-positron emission tomography computed tomography, and pathologic findings and review the relevant literature.

First Vacuum-Assisted Excision of a Breast Myofibroblastoma

A 52-year-old lady was seen in the breast clinic after an 8 mm lesion was found in her left breast on screening mammogram. Clinical examination was normal. The left breast mammogram showed an 8 mm rounded density posteriorly in the inner half of breast and ultrasound also showed a 7 mm, well-defined ovoid echogenic lesion (R3, U3). Biopsy confirmed the lesion was fibro-fatty tissue containing a diffuse infiltrate of lymphoid cells macroscopically (B3/4)—findings in line with a diagnosis of a myofibroblastoma. A myofibroblastoma is a rare benign mesenchymal tumour comprising of spindle cells. Most breast myofibroblastomas described in the literature have been excised by wide local excision. In this patient's case, a vacuum-assisted technique was discussed and suggested at the multidisciplinary meeting. It was excised using ultrasound-guided Vacora® breast biopsy system. The lesion was completely excised with the encore biopsy measuring 24 × 17 mm. This is the first documented case of such a technique for the excision of a breast myofibroblastoma. There still is uncertainty about breast myofibroblastomas, their aetiology, associations, and how they are best investigated. Regarding management, vacuum-assisted technique, being less invasive and cheaper than local excisions, is adequate for small lesions.

Myofibroblastoma of the male breast: a rare entity with radiologic-pathologic correlation

A 73-year old man with a history of multiple genitourinary malignancies was found to have a left retroareolar soft tissue mass on CT assessment of disease, and dedicated breast imaging was recommended. Diagnostic mammography and ultrasonography confirmed a solid mass, for which biopsy was recommended. Pathologic analysis demonstrated a spindle cell neoplasm with an immunoreactivity pattern consistent with myofibroblastoma. While this entity is benign, nonspecific imaging features necessitate tissue sampling for pathologic diagnosis, and, given pathologic rarity, open communication between the radiologist and pathologist is important to establish the correct diagnosis and to recommend appropriate management.

Male breast cellular myofibroblastoma with a rich reticulinic network: case report

Myofibroblastoma is a rare mesenchymal tumor located not only in breast but also in extramammary sites. This is the 79th case of breast myofibroblastoma reported in the literature. This tumor presents a great variety of morphological features, which increase the difficulty of differential diagnosis. The authors report a breast myofibroblastoma diagnosed in a 73-year-old male. The article discusses a bilateral gynecomastia and a palpable right breast well-defined tumor, without calcifications on mammography, which was surgically removed. Macroscopically, a well-circumscribed uncapsulated nodule was seen with lobular arrangement on cut section, and microscopically, a nodule with pushing borders and a connective pseudocapsule was seen. The spindle cells were arranged in fascicular clusters, with focally collagen bundles and a rich reticulinic network stained black with Gömöri impregnation. Immunohistochemically, the tumor cells were marked by vimentin, CD34, desmin, and smooth muscle antigen and did not express cytokeratin, S-100 protein, CD99, CD10, and factor VIII-related antigen. More than 90% of the cells expressed estrogen receptor. No recurrences were reported 2 years after surgical excision. This case is a variant of cellular myofibroblastoma, with a rich reticulinic network and scanty collagen bands.

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.

Benign spindle cell tumors of the mammary stroma: diagnostic criteria, classification, and histogenesis

Purely benign mesenchymal spindle cell neoplasms of the breast are currently labeled under various terms in the literature (benign spindle cell tumor, fibroma, spindle cell lipoma, myofibroblastoma, solitary fibrous tumor, myogenic stromal tumor). The lack of strict diagnostic criteria to clearly indicate such mesenchymal neoplasms is the main reason which generated the risk of terming the same lesion under different names or, conversely, of collecting different types under the same term. Although such neoplasms exhibit morphological and immunophenotypical heterogeneity, they actually represent variations of the same tumor entity, likely arising from the uncommitted vimentin+/CD34+ fibroblasts of the mammary stroma, capable of multidirectional mesenchymal differentiation. To cover the entire spectrum of such lesions, the term "benign spindle cell tumors (BSCTs) of the mammary stroma" is advocated. BSCTs can be subtyped into four main groups by light microscopy (LM) and immunocytochemistry (ICC): fibroblastic, myofibroblastic, fibrohistiocytic, and mixed forms. A simple and practical approach to a nosologically correct diagnosis and a list of differential diagnoses are presented. The awareness of the diversity of morphological and immunophenotypical features of BSCTs of the mammary stroma, including uncommon variants, is helpful to avoid confusion with other monomorphic bland-looking benign and malignant spindle cell tumors and tumor-like lesions of the breast.

Myofibroblastoma of the male breast: imaging appearance and ultrasound-guided core biopsy diagnosis

We present the case of a 78-year-old man with the history of a 14-mm, well-circumscribed mass in the retroareolar region of the right breast. An ultrasound-guided core biopsy showed myofibroblastoma. The mammagraphic and sonographic characteristics of this lesion are described.

Myofibroblastoma of the breast with hemangiopericytoma-like pattern and pleomorphic lipoma-like areas. Report of a case with diagnostic and histogenetic considerations

Myofibroblastoma (MFB) of the breast is an uncommon benign spindle cell tumor which may exhibit a wide spectrum of histological features. We report an unusual case of MFB of the male breast, showing cellular areas with a hemangiopericytoma-like pattern similar to that observed in solitary fibrous tumor (SFT) and extensive fibromyxoid areas containing numerous atypical stromal cells. The association of these atypical cells with mature adipocytes and microcystic and/or myxoid degenerative changes resembled pleomorphic lipoma-like and myxoid liposarcoma-like features, respectively. To our knowledge, these peculiar morphological findings have not been previously reported in MFB of the breast. They should be recognized to avoid confusion with other mesenchymal tumors, especially with hemangiopericytoma, pleomorphic lipoma (PL), spindle-cell lipoma (SCL) and myxoid liposarcoma. A case of MFB of the breast showing morphological features also commonly seen in SFT and PL/SCL is further morphological evidence in support of the speculation that the mesenchymal tumors of the breast, also known under the terms benign spindle cell tumors, fibromas, SFTs, SCLs and MFBs, are histogenetically related lesions.

Breast tumors with myofibroblastic differentiation: clinico-pathological observations in myofibroblastoma and myofibrosarcoma

This report describes the clinico-pathological features of myofibroblastic tumors of the breast in six patients. Four women and one man presented with a benign myofibroblastoma. The sixth patient was a woman with myofibrosarcoma. All myofibroblastomas were composed of a fascicular arrangement of spindle cells embedded in dense bundles of collagen. Tumors differed with respect to their proportion of neoplastic cells and collagenous stroma as well as cellular pleomorphism. Based on this variation, the tumors could be subclassified as classic, collagenized, epithelioid and cellular myofibroblastoma. Immunohistological staining confirmed myofibroblastic differentiation by strong expression of either desmin or smooth muscle actin with coexpression of vimentin. In addition, numerous cells reacted with antibodies to CD68. Proliferative activity was rather low in the myofibroblastoma with an average of 0-2 mitotic figures per 10 HPF. DNA cytometric analysis was performed in two cases and showed diploid stem lines with minor S-phase fractions (1% and 3%). In the myofibrosarcoma, cells contained pleomorphic nuclei with some giant cells and numerous mitotic figures (6-7/10 HPF) and had infiltrating margins that were apparent even grossly. Immunohistochemically, tumor cells strongly expressed vimentin, smooth muscle actin and fibronectin. Ultrastructurally, neoplastic cells met the criteria of myofibroblasts, i.e. contained abundant intermediate filaments and myofilament bundles with focal densities as well as fibronexus junctions. DNA cytometric analysis exhibited again a diploid stemline but marked proliferative activity was present as indicated by an S-phase fraction of 20%. In conclusion, in benign myofibroblastoma there may be some cellular pleomorphism but mitotic activity is always low. The malignant counterpart, myofibrosarcoma, is characterized by marked cellular pleomorphism, infiltrating margins and high mitotic rate.

Benign spindle cell tumor of the breast with prominent adipocytic component

We report a rare case of "benign spindle cell tumor of the breast with prominent adipocytic component" and present a review of the literature on the topic. The close morphologic resemblance with myofibroblastoma and spindle cell lipoma of the breast is emphasized and used as a starting point for diagnostic and histogenetic considerations. Although immunocytochemistry and electron microscopy showed features favoring a diagnosis of spindle cell lipoma, they were not conclusive. The tumor described here contributes to widen the spectrum of the benign spindle cell tumors of the breast variously named "benign spindle cell tumor," myofibroblastoma, spindle cell lipoma, and fibroma. It is important to distinguish this lesion from spindle cell metaplastic carcinoma and aggressive fibromatosis.