MR imaging of the penis: What a radiologist needs to know!

Magnetic resonance imaging (MRI) plays an important role in imaging of penile pathologies due to its excellent soft tissue resolution and multiplanar imaging capabilities. This imaging review describes the MRI protocols and anatomical considerations in penile pathologies. MRI not only serves as a complementary tool to ultrasound in evaluation of trauma, infections, inflammatory diseases, and malignancies, but is also used as the definitive imaging modality for evaluation of penile prosthesis and complex cases.

Diagnostic Approach to Mesenchymal and Spindle Cell Tumors of the Breast

Mesenchymal and spindle cell tumors of the breast represent a broad and heterogeneous group of lesions that may be sampled on core needle biopsy or surgical excision. Mesenchymal lesions unique to the breast are those that derive from the specialized breast myofibroblast, such as mammary myofibroblastoma and pseudoangiomatous stromal hyperplasia. However, any mesenchymal lesion arising in extramammary soft tissue may also arise in the breast, including fibroblastic, peripheral nerve sheath, adipocytic, and vascular lesions. The spindle cell lesions pose the greatest diagnostic challenge, due to the significant radiographic, morphologic, and immunophenotypic overlap within the category of mesenchymal lesions and more broadly with other nonmesenchymal breast lesions. The distinction is particularly challenging on the limited material of breast core needle biopsies, and caution should be taken before definitively classifying a breast spindle cell lesion on core needle biopsy to avoid unnecessary treatment if misdiagnosed. Consideration of a wide differential diagnosis, adequate sampling of a resection specimen, use of a targeted immunopanel, and selective use of molecular assays are essential steps for accurate classification of mesenchymal lesions in the breast. This review covers the clinical, histologic, and immunophenotypic features of mesenchymal tumors of the breast, with a special emphasis on the differential diagnoses unique to the breast and challenges encountered on breast core needle biopsy.

Case report: A challenging case of mixed-variant myofibroblastoma with complex imaging and pathological diagnosis

Myofibroblastomas are benign mesenchymal tumors that frequently occur in the groin. They show variable morphology, and the differential histopathological diagnoses are broad, including lipomatous to myxoid tumors. In addition, both pathological and imaging findings may be complex, which makes diagnosis challenging. We herein present a case of a mixed-variant myofibroblastoma of the wrist in a 73-year-old woman. Considering the long clinical course of more than 20 years and the imaging findings, a benign myxoid tumor including a schwannoma was suspected; however, the histopathological findings from resected specimens suggested a diagnosis of myxofibrosarcoma. Additional histopathological findings led to a diagnosis of mixed-variant myofibroblastoma. The differential diagnosis of myofibroblastoma extends beyond imaging to pathological findings because of the number of possible variants. This case reinforces the notion that the gold standard treatment for soft tissue tumors is to perform surgery only after determining the correct diagnosis by biopsy.

A Case of Mammary-Type Myofibroblastoma Occurring in the Inguinal Region

Mammary-type myofibroblastoma (MTMF) is a rare benign tumor of mesenchymal cells that occurs in the inguinal region, abdominal wall, buttocks, back, and vaginal wall. When a soft tissue mass develops in the inguinal region, there may be a risk of misdiagnosing it as an inguinal hernia, especially if it is asymptomatic. We report a rare case of mammary-type myofibroblastoma occurring in the inguinal region. The patient was a 40-year-old male who noticed swelling in the right inguinal region two years prior and consulted a nearby medical clinic. He was diagnosed with a right inguinal hernia and referred to our hospital. On physical examination, a protrusion was observed in the right inguinal region, and due to difficulty in reduction, emergency surgery was performed, suspecting intestinal incarceration. Intraoperatively, no inguinal hernia was found, but a mobile yellowish mass was identified. There were no malignant features, and the mass was excised. The pathological examination revealed mammary-type myofibroblastoma. When we examine a patient with a complaint of inguinal swelling, it is important to consider not only inguinal hernia but also other conditions such as soft tissue tumors.

Myofibroblastoma in the Liver: A Case Report and Review of Literature

Myofibroblastoma is a rare benign mesenchymal tumor first described in the breast. It is also known as mammary-type myofibroblastoma outside of the breast, more frequently located along the embryonic milk line. Exceptionally, myofibroblastoma can occur at visceral locations. We present a case of myofibroblastoma detected incidentally in the liver. A well-circumscribed mass, grossly measuring 6.2 cm in the liver parenchyma, was found on imaging studies. Histologically, the lesion is characterized by benign spindle cells in a hyalinized collagenous stroma, with positive staining for SMA and ER, focal positivity for CD34, negative for desmin, and loss of RB1. This rare tumor at such an unusual location makes it diagnostically challenging, especially on core biopsy of the lesion. To our knowledge, this is the second case of myofibroblastoma in the liver reported in the English literature and the first such case with a detailed pathology description.

Immunohistochemistry in the Diagnosis and Classification of Breast Tumors

CONTEXT.—

In the clinical practice of breast pathology, immunohistochemistry (IHC) of different markers is widely used for the diagnosis and classification of breast lesions.

OBJECTIVE.—

To provide an overview of currently used and recently identified IHC stains that have been implemented in the field of diagnostic breast pathology.

DATA SOURCES.—

Data were obtained from literature review and clinical experience of the authors as breast pathologists.

CONCLUSIONS.—

In the current review, we summarize the common uses of IHC stains for diagnosing different types of breast lesions, especially invasive and noninvasive breast lesions, and benign and malignant spindle cell lesions. In addition, the cutting-edge knowledge of diagnostic carcinoma markers will lead us to further understand the different types of breast carcinoma and differentiate breast carcinomas from other carcinomas of similar morphology. Knowing the strengths and limitations of these markers is essential to the clinical practice of breast pathology.

An Immunohistochemical Anomaly: A Case Report and Systematic Review of Myofibroblastoma of the Breast

Myofibroblastoma (MFB) is a rare but benign mesenchymal tumor most commonly appearing within breast tissue. Most cases of MFB occur in postmenopausal women and are treated by surgical excision. The diagnosis of MFB is made through immunohistochemical (IHC) analysis, with the most common biomarkers being CD34+, desmin+, smooth muscle actin+, and vimentin+. In this article, we describe a case of an MFB in a premenopausal female with variance from classic IHC findings. We also performed a systemic review of the MFB of the breast. The systemic review compiles the most common IHC findings of MFB, patient demographics, treatment methods, lesion size, and the presence or absence of pain associated with the lesion. As MFB can share many features with other breast lesions, including potentially malignant ones, this article sought to underline the most common IHC findings and characteristics of MFB to aid in the proper diagnosis of MFB.

Mammary myofibroblastoma: Presentation of case

INTRODUCTION AND IMPORTANCE

Mammary myofibroblastoma (MFB) is a rare benign mesenchymal lesion. It belongs to the family of benign spindle cell tumours of the mammary stroma and may exhibit confusing variants. Some of them may mimic invasive tumours, leading to the diagnostic dilemmas, especially in core needle biopsy specimens or frozen sections. Familiarity with the characteristics of this tumour is of great importance for accurate diagnosis and proper treatment.

CASE PRESENTATION

We report about a rare form of CD34-negative mixed epithelioid/lipomatous form of mammary myofibroblastoma in a 48-year-old Caucasian premenopausal woman with no previous medical history. Breast imaging suggested a benign lesion. The core needle biopsy suggested breast MFB. The definitive diagnosis was established through histopathology and immunohistochemistry of the lumpectomy specimen.

CLINICAL DISCUSSION

Despite its rarity, breast MFB is a disease with a wide spectrum of histologic morphologies. CD34 positivity is seen in majority of MFB cases. MFBs uncommonly show absent expression of CD34, a potential diagnostic pitfall, just like in our case.

CONCLUSION

Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis. Surgical excision is at present the ordinary treatment of MFB.

Spindle Cell Lesions of the Breast: A Diagnostic Algorithm

CONTEXT.—

Spindle cell lesions of the breast represent a broad spectrum of entities, ranging from nonneoplastic reactive conditions to high-grade malignant tumors. The wide range makes breast spindle cell lesions a diagnostic pitfall.

OBJECTIVE.—

To review the classification of spindle cell lesions of the breast, including clinical features, morphologic characteristics, and the role of immunohistochemistry as well as molecular tools in assisting the differential diagnosis. A diagnostic algorithm will be proposed.

DATA SOURCES.—

Literature and personal experience are the sources for this study.

CONCLUSIONS.—

Spindle cell lesions of the breast can be classified as biphasic or monophasic, with the former including both spindle cell and epithelial components, and the latter including only spindle cell elements. Each category is further subclassified as low or high grade. In the biphasic low-grade group, fibroadenoma and benign phyllodes tumor are the most common lesions. Other uncommon lesions include hamartoma, adenomyoepithelioma, and pseudoangiomatous stromal hyperplasia. In the biphasic high-grade group, borderline/malignant phyllodes tumor and biphasic metaplastic carcinoma are the main lesions to consider. In the monophasic low-grade group, reactive spindle cell nodule, nodular fasciitis, myofibroblastoma, fibromatosis, and fibromatosis-like metaplastic carcinoma have to be considered. In the monophasic high-grade group, the possible lesions are monophasic spindle cell metaplastic carcinoma, primary breast sarcoma, and metastases. Awareness of the clinical history and careful evaluation of any epithelial differentiation (with a large immunohistochemical panel) are crucial in the distinction.

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.

A rare case of myofibroblastoma in an older male

Myofibroblastoma is a rare benign breast stromal tumor comprised of fibroblasts and myofibroblasts, most commonly presenting in postmenopausal women and older men. This report discusses the case of a 69-year-old male diagnosed with myofibroblastoma after mammography, targeted ultrasound, and core needle biopsy of a retroareolar mass. The features of myofibroblastoma are presented.

Low to Intermediate (Borderline) Grade Breast Spindle Cell Lesions on Needle Biopsy: Diagnostic Approach and Clinical Management

Spindle cell proliferations of the breast are a heterogeneous group of lesions ranging from benign or reactive lesions to aggressive malignant neoplasms. Diagnosis on core biopsy can be particularly challenging as lesions displaying different lineages associated with variable outcomes share overlapping morphologies (scar vs. fibromatosis-like metaplastic carcinoma) whereas individual entities can exhibit a large variety of appearances (myofibroblastoma). In this review, lesions are grouped into lineage, when possible, including those showing fibroblastic/myofibroblastic differentiation, ranging from entities that require no additional management, such as scar and nodular fasciitis, to those with unpredictable clinical outcomes such as fibromatosis and solitary fibrous tumor or locally aggressive behavior such as dermatofibrosarcoma protuberans. The review of low-grade vascular lesions includes atypical vascular lesion and low-grade angiosarcoma. Also discussed are various adipocytic lesions ranging from lipoma to liposarcoma, and rare smooth muscle and neural entities more commonly encountered in locations outside the breast, such as leiomyoma, neurofibroma, schwannoma, or granular cell tumor. Optimal histological evaluation of these entities merges clinical and radiologic data with morphology and ancillary testing. We present our approach to immunohistochemical and other ancillary testing and highlight issues in pathology correlation with imaging. Recent updates in the management of breast spindle cell lesions are addressed. In a well-sampled lesion with radiographic concordance, the core biopsy diagnosis reliably guides management and we advocate the inclusion of management recommendations in the pathology report. Precise characterization using up to date guidelines is important to identify a subset of patients who may safely avoid unnecessary surgical procedures. A multidisciplinary approach with close collaboration with our clinical colleagues is emphasized.

Retroperitoneal myofibroblastoma in an 88‐year‐old male

Introduction

Extramammary myofibroblastomas are extremely rare.

Case presentation

The patient was an 88‐year‐old male. He presented for evaluation of frequent urination and a “pushing up” sensation from the groin during defecation. Thorough physical and radiographic examinations revealed a retroperitoneal tumor on the right side of the rectum. The pathologic examination of the biopsy tissue showed that the tumor was unlikely to be malignant. Nevertheless, the patient was symptomatic and thus underwent a laparoscopic tumor resection through a transperitoneal approach. The tumor was circumscribed with a solid capsule. Based on the pathologic findings, which included immunostaining, the tumor was diagnosed as a myofibroblastoma. There was no evidence of a recurrence 6 months postoperatively.

Conclusion

We present this case with the clinical course and surgical findings, and discuss the possibility of establishing a preoperative pathologic diagnosis of a myofibroblastoma.

Epithelioid myofibroblastoma of the breast: A case report and review of the literature

INTRODUCTION

Mammary myofibroblastoma (MFB) is a rare tumour. Its clinical and pathologic characteristics have been only sporadically described. A case of epithelioid variant of MFB is reported with the diagnostic tips, the differential diagnoses, and a discussion on the possible pathogenesis.

PRESENTATION OF CASE

A 74 year-old woman presented with a painless nodule in the left breast. Core needle biopsy (CNB) revealed a tumour primarily composed of epithelioid cells. Despite epithelioid appearance of the tumour cells, ductal/lobular components were absent within the tumour. As cell lineage of the epithelioid cells could not be determined with CNB, lumpectomy was performed to obtain definitive diagnosis and, at the same time, to remove the lesion. Histologically, the tumour consisted of multiple epithelioid cell nests that were spread over fibrous stroma infiltrated with adipose tissue. Spindle cells were also present, but they were fewer than epithelioid cell clusters. Occasionally, the tumour cells showed nuclear atypia. It was difficult to determine whether this tumour was benign or malignant solely with Hematoxylin-eosin stain. However, with the aid of immunohistochemical analyses, we could make a histodiagnosis of epithelioid subtype of myofibroblastoma.

DISCUSSION

The differential diagnoses of epithelioid MFB include ductal, lobular, metaplastic carcinomas and mesenchymal tumours. Comprehensive knowledge of classic and variant MFB is necessary for the correct diagnosis.

CONCLUSION

Pathologic diagnosis of epithelioid variant of MFB requires careful evaluation of histology and the use of a panel of immunohistochemistry. Female phenotype of breast stroma may play a role in the pathogenesis of MFB.

Myofibroblastoma of the Breast: Diagnosis, Pathology, and Management

Myofibroblastomas are rare benign spindle cell tumors that occur within both male and female breasts. They are composed of fibroblasts and myofibroblasts and are not associated with malignant potential. On mammographic and sonographic imaging, these tumors may present as oval circumscribed masses that overlap with the appearance of many benign entities, including fibroadenomas. Occasionally, the tumors may demonstrate interval growth or mimic imaging features of malignancy and require biopsy. Correct pathologic diagnosis is important because many morphologic variants exist, which complicates pathologic interpretation. The purpose of this article is to review the range of imaging manifestations and histopathological findings and to discuss current management.

Mammary-type myofibroblastoma with infarction and atypical mitosis-a potential diagnostic pitfall: A case report

BACKGROUND

Mammary-type myofibroblastoma (MTMF) is a rare benign extramammary soft tissue tumor with myofibroblastic differentiation. Although 160 cases of MTMF have been reported in the literature since 2001, no cases of infarction or atypical mitosis have been reported so far. Herein, we report an unusual case of MTMF in the pelvic cavity, which mimicked some malignant features, including infarction, atypical mitosis, infiltrative growth, and prominent cytologic atypia, making it difficult to ascertain whether the tumor was benign.

CASE SUMMARY

A 49-year-old man complained of pain and discomfort in the right buttock for more than 4 mo and did not receive any treatment. Nuclear magnetic resonance imaging (MRI) showed a 13-cm-sized mass in his right pelvic cavity. Histologically significant differences were atypical mitosis figures and multiple necrotic foci in the tumor. In addition, smooth muscle and skeletal muscle were invaded within and at the edge of the tumor. These morphologic features are often reminiscent of malignant tumors and therefore pose a diagnostic challenge to pathologists. The tumor cells were strongly positive for both cluster of differentiation 34 and desmin, and the loss of retinoblastoma 1 shown by immunohistochemical and fluorescence in situ hybridization results confirmed the pathological diagnosis of MTMF. Currently, the patient is alive and in good condition without tumor recurrence or metastasis after 2.5 years of follow-up by telephone and MRI.

CONCLUSION

The two pseudo-malignant characteristics of infarction and atypical mitosis broaden the morphological lineage of MTMF, a rare mesenchymal tumor.

Angiomyofibroblastoma and Potential Mimicking Soft Tissue Tumors That May Occasionally Present in the Retroperitoneum: An Approach to the Differential Diagnosis With Report of an Unusual Index Case Abutting the Kidney

The retroperitoneal soft tissues, extending from the pelvic floor to the level of the diaphragm, are the source of a variety of mesenchymal neoplasms with overlapping features and distinct clinical behaviors, making their distinction of crucial importance. Herein, we report a rare retroperitoneal angiomyofibroblastoma (AMFB) that presented as a right abdominal mass in a 25-year-old woman and that clinically simulated a primary renal carcinoma. The patient underwent complete surgical resection showing a well-circumscribed tumor adjacent to but separate from the right kidney. It was comprised of irregular, often anastomosing islands and cords of plump to spindled cells in a collagenous stroma with numerous thin-walled vessels. The tumor cells clustered around the vessels and admixed with moderate numbers of adipocytes. There was neither significant nuclear atypia nor mitotic activity. Immunohistochemically, the tumor cells showed strong reactivity for desmin, diffuse expression of estrogen and progesterone receptors, retained nuclear expression of retinoblastoma protein, and absent CD34 expression. The immunomorphological features were these of a "lipomatous variant" of AMFB of the retroperitoneum. The occurrence of AMFB in the retroperitoneum is unexpected since it mostly develops in the lower genital tract of young women, making its recognition in this rare location difficult. As a consequence, more common pelvic or retroperitoneal soft tissue neoplasms may represent the primary diagnostic considerations. We, therefore, review a variety of soft tissue tumors occurring in the pelvis/retroperitoneum that, to some degree, may mimic AMFB, and present key findings to assist in accurate diagnosis.

Diagnostic challenges of intra-operative frozen consultation for mammary epithelioid myofibroblastoma

Myofibroblastoma (MFB) of the breast is a rare benign neoplasm that exhibits several morphologic variants and presents diagnostic challenges for pathologists, especially in recognizing intra-operative frozen sections. In order to raise awareness of this tumor and avoid misdiagnosis, we describe a case of a 38-year-old female patient diagnosed as epithelioid MFB. This painless tumor was well-circumscribed, found in the left breast and was physically examined over a period of six months. Histologically, this tumor was predominantly composed of epithelioid cells, which arranged as single cells, small clusters or nests. Tumor stroma was collagenized with spindle cells, adipose and focal myxoid areas. This case was misinterpreted as invasive carcinoma in the frozen section. The immunohistochemical profile demonstrated positivity for Vimentin, desmin, SMA, calponin, CD34, ER, PR and AR, whereas pan-keratin, keratin 7, keratin 34βE12, keratin 5/6, EMA, p63 and S100 were negative. RB1 was abnormally negative, confirming the diagnosis of epithelioid MFB. Making a correct diagnosis is primarily dependent on awareness by the pathologist of this unusual variant of MFB and careful integration of clinicopathologic findings to avoid potential diagnostic pitfalls.

Unexpected hyperechoic lesions of the breast and their correlations with pathology: a pictorial essay

Hyperechoic lesions of the breast encompass a wide range of conditions that are occasionally encountered during breast ultrasonography. Although typical hyperechoic lesions with a distinct fat component on imaging are well known, some hyperechoic lesions are diagnosed as unexpected pathology, making the radiology-pathology correlation difficult. Therefore, understanding the pathology of these lesions and how it correlates with imaging findings can help radiologists accurately diagnose and properly manage a range of related conditions. This article presents a pictorial review of unexpected hyperechoic benign and malignant breast lesions, with a focus on the pathological conditions that give rise to the hyperechoic pattern.

Myofibroblastic stromal hyperplasia of the breast

Myofibroblastic stromal hyperplasia (MSH) is the proposed name for a benign spindle cell proliferation of the mammary stroma, which often raises clinical and radiographic concern for a mass or a malignant process. Ten cases were retrieved from the files of our institution. All presented as a mammographic abnormality. Patients ranged in age from 24 to 67 years. Seven were <50 years old. The salient histopathologic aspect was the proliferation of benign appearing spindle cell within the intralobular stroma. The most common pattern was a diffuse proliferation of compact spindle cells with areas of perilobular/periductal accentuation. Mitotic activity and atypia were not seen. Tumor cells were positive for CD34 and SMA and negative for estrogen receptor, Beta-catenin, and p63. Only one of the cases demonstrated an associated lesion that explained the mammographic abnormality. Follow-up was available for four cases and was uneventful. MSH has overlapping features with the fascicular pattern of PASH and is likely related to pseudoangiomatous stromal hyperplasia (PASH) but differs in that does not demonstrate pseudovascular structures and it predominantly involves perilobular stroma. Recognition of this pattern will avoid discordant radiologic pathologic findings and unnecessary surgery/repeat biopsies.

Myofibroblastoma of the Breast: A Morphologic and Immunohistochemical Study of Three Cases

Myofibroblastoma (MFB) of the breast is an uncommon entity of benign spindle neoplasms of the breast. This tumour possesses a broad spectrum of histomorphological patterns. Distinguishing of myofibroblastoma variants from malignant mimics of this benign neoplasm is essential for pathologists to avoid further invasive surgical procedures. In this article, we report the clinical, morphological, and immunohistochemical features of three cases, including two females and one male patient with mammary myofibroblastoma with emphasis on the histomorphological findings. As there is not yet enough information about MFB, more reports of MFB are still required to more clarify the pathogenesis and potential predisposing factors of this rare type of breast tumours.

Benign myofibroblastic/epithelial lesions of the breast with minimally infiltrative margins

A minority of mixed fibro-epithelial lesions of the breast lacks both fibroadenoma and phyllodes architectural patterns and have been previously labeled with different terms, including "hamartomas", "myoid/muscular hamartomas", "benign fibroadenomatous lesions" or "stromo-epithelial lesions of the breast". This study emphasizes the clinico-pathologic features of 5 cases of mammary benign fibro(stromo)-epithelial lesions sharing as a common morphologic theme the presence of minimally infiltrative margins due to the overgrowth of the stromal component into the surrounding fibro-fatty tissue. Notably the radiological features were suspicious for malignancy in 3 out of 5 cases. The following histologic features were seen in all cases: i) an epithelial component of benign glandular structures exhibiting the morphological spectrum of fibro-cystic disease; ii) a stromal component of bland-looking spindle cell myofibroblasts (vimentin + and α-smooth muscle actin +) set in a variably fibro-myxoid stroma. The present paper contributes to widen the morphological spectrum of the benign fibro-epithelial lesions of the breast, emphasizing the possibility that some cases, exhibiting a predominant myofibroblastic stromal component and minimally infiltrative margins, may be confused with other primary spindle cell mimickers of the breast. Accordingly, we propose the descriptive term "benign myofibroblastic/epithelial lesions of the breast with minimally infiltrative margins" for these previously underrecognized lesions.

Mammary-type Myofibroblastoma with Leiomyomatous Differentiation: A Rare Variant with Potential Pitfalls

Myofibroblastoma is a rare, benign stromal tumor with a diverse morphologic spectrum. Mammary-type myofibroblastoma (MTMF) is the extra-mammary counterpart of this neoplasm and its occurrence throughout the body has become increasingly recognized. Similar morphologic variations of MTMF have now been described which mirror those seen in the breast. We describe a case of intra-abdominal MTMF composed of short fascicles of eosinophilic spindle cells admixed with mature adipose tissue. The spindle cells stained diffusely positive for CD34, desmin, smooth muscle actin, and h-caldesmon by immunohistochemistry. Concurrent loss of RB1 (13q14) and 13q34 loci were confirmed by fluorescence in situ hybridization whereas anchored multiplex PCR and whole transcriptome sequencing did not reveal any pathognomonic fusions suggesting an alternative diagnosis. To the best of our knowledge this is the first documented case of leiomyomatous variant of MTMF.

Spindle cell lesions of the breast: a diagnostic approach

Spindle cell lesions of the breast comprise a heterogeneous group of lesions, ranging from reactive and benign processes to aggressive malignant tumours. Despite their rarity, they attract the attention of breast pathologists due to their overlapping morphological features and diagnostic challenges, particularly on core needle biopsy (CNB) specimens. Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis and to suggest proper management of the patients. Clinical history, immunohistochemistry, and molecular assays are helpful in making a correct diagnosis in morphologically challenging cases. In this review, we present our approach for the diagnosis of breast spindle cell lesions, highlighting the main features of each entity and the potential pitfalls, particularly on CNB. Breast spindle cell lesions are generally classified into two main categories: bland-appearing and malignant-appearing lesions. Each category includes a distinct list of differential diagnoses and a panel of immunohistochemical markers. In bland-appearing lesions, it is important to distinguish fibromatosis-like spindle cell metaplastic breast carcinoma from other benign entities and to distinguish fibromatosis from scar tissue. The malignant-appearing category includes spindle cell metaplastic carcinoma, stroma rich malignant phyllodes tumour, other primary and metastatic malignant spindle cell tumours of the breast, including angiosarcoma and melanoma, and benign mimics such as florid granulation tissue and nodular fasciitis.

Myofibroblastoma of the breast showing rare palisaded morphology and uncommon desmin- and CD34-negative immunophenotype: A case report

Myofibroblastoma is a rare benign mesenchymal tumor typically arising in the breast. We report a diagnostically challenging case of myofibroblastoma of the breast showing a rare palisaded morphology and an uncommon desmin- and CD34-negative immunophenotype. A 73-year-old man underwent an excision for an 8 mm-sized breast mass. Histology revealed that the tumor was composed of fascicles of bland spindle cells showing prominent nuclear palisading and Verocay-like bodies. First, schwannoma, malignant peripheral nerve sheath tumor, and synovial sarcoma were suspected given the palisaded morphology. However, none of them was confirmed by immunohistochemical or molecular analyses. Next, a palisaded variant of myofibroblastoma was suspected by the morphology and coexpression of estrogen, progesterone and androgen receptors, BCL2 and CD10 in immunohistochemistry. However, the key diagnostic markers, desmin and CD34, were both negative. Finally, the diagnosis of myofibroblastoma was confirmed by detecting RB1 loss in immunohistochemistry and monoallelic 13q14 deletion (RB1 and FOXO1 loss) by fluorescence in situ hybridization assay. For the correct diagnosis of myofibroblastoma, it is important for pathologists to recognize the wide morphological spectrum, including a palisaded morphology, and the immunophenotypical variations, including desmin- and CD34-negative immunophenotypes, and to employ a comprehensive diagnostic analysis through combined histological, immunohistochemical and molecular evaluations.

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.

A case of mammary myofibroblastoma diagnosed with cytomorphological, cell block and immunohistochemistry findings

Myofibroblastoma (MFB) is a rare benign spindle cell tumor originating from myofibroblasts in the breast stroma. MFB typically presents as a slow-growing, well-circumscribed, solitary mass ranging from 1 to 4 cm in size. It has been reported in adults, and frequently seen in older males and in postmenopausal females. The lesion is composed of stromal cells showing fibroblastic and myofibroblastic differentiation at the morphological, immunohistochemical and ultrastructural levels. To date, the literature includes only about 24 MFB cases confirmed via fine-needle aspiration and cytological evaluation. Here, we present a patient with MFB that was diagnosed via conventional smear slides and cell block, in addition to immunohistochemical analysis.

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.

A Novel Case of Mammary-Type Myofibroblastoma With Sarcomatous Features

Mammary-type myofibroblastoma (MFB) is a benign spindle cell tumor of the breast and soft tissue characterized by 13q14 alterations leading to loss of Rb-1 protein expression, a feature shared among spindle cell lipoma and cellular angiofibroma. In this article, we present a novel case of MFB arising in the left breast of a 70-year old man that microscopically showed an abrupt transition from classic MFB morphology to an area with cytologic atypia and mitotic activity, akin to sarcomatous transformation described in cellular angiofibromas. A thorough workup of the molecular underpinnings of both components using chromosomal microarray and next-generation sequencing platforms supported a clonal relationship. Nearly identical copy number changes, including a single copy loss of 13q14, were found in both components; in addition, the sarcomatous component harbored biallelic TP53 alterations. It is important for pathologists to recognize that sarcomatous features can occur in mammary-type MFB to arrive at the correct diagnosis.

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.

A novel collision tumour of myofibroblastoma and low-grade adenosquamous carcinoma in breast

BACKGROUND

Myofibroblastoma (MFB) and low-grade adenosquamous carcinoma (LGASC) are rare tumours in the breast, respectively. However, a collision tumour of the two types has never been reported.

CASE PRESENTATION

A 42-year-old female presented with a palpable mass in diameter of about 2.5 cm in the left breast. Morphologically, the lesion was predominately composed of bland spindle cells admixed with some islands of mature adipocytes and a few epithelial elements dispersing in infiltrating way which formed both tubule and solid structures. The mass showed low positive index of Ki-67. The spindle cells were strongly and diffusely positive for CD34, SMA, desmin, ER and PR. The epithelial elements were positive for CK and EMA, and negative for ER and PR completely. CK5/6 and P63 were positive in the outer-layer of the tubules and nearly all the cells of the solid nests.

CONCLUSIONS

A collision tumour of MFB and LGASC in breast is extremely rare and either component is supposed to be not overlooked. Excision and close follow-up are advised.

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.

Male mammary myofibroblastoma: Two case reports and brief review of literature

Myofibroblastoma of the breast is a rare benign stromal tumor that occurs in both sexes with a higher prevalence in male breast of older populations. Furthermore, myofibroblastoma can arise in extra mammary sites, along the milk-line. A variety of morphological variants in addition to the classic type have been identified. The differential diagnosis includes both benign and malignant entities that, through the use of clinical and radiological imaging, is difficult to characterize. Histopathological examination and immunohistochemistry are fundamental in the establishment of appropriate management of the disease and avoidance of overtreatment. The present study focuses on two cases of male mammary myofibroblastoma, with a short literature review.

A review of mucinous lesions of the breast

Mucinous lesions of the breast include a variety of benign and malignant epithelial processes that display intracytoplasmic or extracellular mucin, including mucocele-like lesions, mucinous carcinoma, solid papillary carcinoma, and other rare subtypes of mucin-producing carcinoma. The finding of free-floating or stromal mucin accumulations is a diagnostic challenge of which the significance depends on the clinical, radiologic, and pathologic context. This article emphasizes the differential diagnosis between benign and malignant mucin-producing lesions, with a brief consideration of potential mimics, such as biphasic and mesenchymal lesions with associated with mucinous, myxoid, or matrix material.

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.

A case report of a mammary myofibroblastoma in a male and literature review of radiologic and pathologic features of breast myofibroblastoma

We reported a 65-year-old male with a benign mammary myofibroblastoma. This report shows that not all masses of male breast are malignant. To differentiate benign masses from malignant neoplasms, careful preoperative diagnosis should be performed. Preoperative diagnosis of the tumor prevents placing a huge financial and mental burdens on patients.

Rare Mesenchymal Breast Entities that Mimic Malignancy: A Single-institution Experience of a Challenging Diagnosis

Background

Benign mesenchymal tumors of the breast are rare and may mimic invasive carcinoma on imaging and morphology, thus becoming clinically challenging for clinicians, radiologists, and pathologists. To improve the understanding of these lesions and to avoid erroneous diagnosis and inappropriate treatment, we report our institution’s experience with seven cases of granular cell tumor (GCT) and myofibroblastoma (MFB) in the past 10 years.

Materials and methods

Seven cases of benign mesenchymal tumors of the breast were identified at the University of Texas Medical Branch from 2008 to 2018. Breast biopsies were collected from all patients after mammography and ultrasound imaging classified their results as suspicious or highly suggestive of malignancy by the Breast Imaging Reporting and Data System (BI-RADS ≥ 4A). All cases were reviewed to study the morphologic features and their immunoprofiles. The demographic characteristics, methods of treatment, postoperative pathological results, and follow-up results of the cases were then analyzed and compared to peer-reviewed literature.

Results

The study consisted of five females and two males with a mean age of 50 years in the GCT patients and 62 years in MFB patients. We identified four cases of GCT and three cases of MFB. The mean tumor size was 1.9 cm. Clinically, five patients presented with a palpable nontender mass, one with breast asymmetry, and one was asymptomatic. All patients underwent imaging studies prior to core needle biopsy. BI-RADS was ≥4B in patients with GCT and 4A-C in MFB. Definitive diagnosis was made by histopathology and confirmed by immunohistochemistry in accordance with the features described in the literature. Six patients underwent wide excision. The mean follow-up duration was 44.5 months. All patients remained well, without recurrence.

Conclusions

MFB and GCT can mimic malignant neoplasms and the clinical significance of these entities lies primarily in their recognition as distinctive benign neoplasms. The gold standard for the diagnosis of GCT and MFB is histopathology. All the cases in our series were clinically or radiologically mistaken for carcinoma, which has been largely reported in the literature. Pathologists should bear this in mind to avoid misdiagnosis and unnecessary treatment.

Myxoid Myofibroblastoma of the Breast With Atypical Cells

The differential diagnosis of myxoid lesions in the breast is broad and includes both benign and malignant entities. Assessment is particularly challenging on core biopsy specimens. Myofibroblastoma, initially thought to be more common in the adult male breast, is being recognized with increasing frequency in the female breast. The wider anatomic distribution of mammary-type myofibroblastoma has also become known, and many new morphological variants have been described. Though focal myxoid stroma may be noted in myofibroblastomas and occasional myofibroblastomas may contain atypical cells, there have been only 3 reports in the literature of myofibroblastomas with exclusive or predominantly myxoid stroma, and 2 of these contained atypical cells. We report another case of mammary myxoid myofibroblastoma with atypical cells in a 40-year-old woman and discuss the differential diagnoses of myxoid lesions in the breast.

Detection of bovine papillomavirus type 2 DNA in calf conjunctival myofibroblastoma

An 8-month-old male Japanese Black calf was referred for the evaluation of a slow-growing conjunctival mass in the right eye. A superficial keratectomy was performed followed by recurrence on two occasions. No metastases were found in surrounding tissues. Histological, immunohistochemical, and ultrastructural investigation revealed that both the primary and the recurrent lesions were benign, conjunctival, myofibroblastomas. Interestingly, bovine papillomavirus type 2 (BPV-2) DNA was detected in both myofibroblastoma lesions. Archival bovine myofibroblastomas from the vulva and neck were also analyzed for papillomaviral genomes. BPV-2 DNA was also amplified from these lesions. To the best of our knowledge, this is the first report describing a potential causal relationship between BPV-2 infection and conjunctival myofibroblastoma.

Utility of STAT6 and 13q14 deletion in the classification of the benign spindle cell stromal tumors of the breast

The boundaries of the benign spindle cell stromal tumors of the breast are still confusing. This is the reason why different names are interchangeably used for the same tumor and vice versa the same name for different tumors. Therefore, we studied the immunoexpression of easily available markers, such as CD34, α-smooth muscle actin, and desmin, with the addition of STAT6, as well as the chromosome 13q14 region by fluorescence in situ hybridization analysis in a series of 19 cases of benign spindle cell stromal tumors of the breast. Based on the morphologic and immunohistochemical findings, the following histotypes were identified: (i) tumors (10/19 cases) with the characteristic morphology of myofibroblastoma and stained with vimentin, CD34, desmin, and α-smooth muscle actin; (ii) fibroblastic benign spindle cell tumors (5/19 cases) composed of fibroblast-like cells stained only with vimentin and CD34; (iii) tumors (2/19 cases) with the typical morphologic features of solitary fibrous tumor and stained with vimentin, CD34, and STAT6; (iv) 1 case of spindle cell lipoma stained with vimentin and CD34; and (v) 1 case of fibroma composed of a paucicellular, diffusely hyalinized stroma with expression of vimentin and CD34. Notably most of the tumors, with the exception of solitary fibrous tumor, showed monoallelic deletion of FOXO1. This finding supports that myofibroblastoma, fibroblastic benign spindle cell tumor, spindle cell lipoma, and fibroma of the breast are histogenetically related lesions which belong to the same tumor entity.

Multimodality images of myofibroblastoma in the male breast: A case report and a review of the literature

We report a case of a 58-year-old male diagnosed with myofibroblastoma using mammography, ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI), as well as present a review of the literature. The pathological diagnosis was myofibroblastoma with spindle cell neoplasm with immunoreactivity. Myofibroblastoma is a rare benign disease and there is a lack of reports of multimodality imaging of this disease. We review the imaging features of this rare disease across multiple imaging modalities with pathological correlation, and provide current treatment recommendations as well.

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.