Vulvovaginal angiomyofibroblastomas: morphologic, immunohistochemical, and fluorescence in situ hybridization analysis for deletion of 13q14 region

Giant Angiomyofibroblastoma With a Florid Lipomatous Component: A Report and Review of Diagnostic Considerations

Angiomyofibroblastoma is a benign, usually small neoplasm typically constituted by spindle-shaped and epithelioid cells in a vascularized, myxoid-fibrous stromal background. It is most often seen in the superficial genitalia of female patients of reproductive age. However, various clinical and histologic features have been reported, including tumors in male patients, malignant transformation, extragenital sites, huge sizes, and a prominent lipomatous pattern. We report the clinical and pathologic features of one such tumor: a 23.5 cm lipomatous angiomyofibroblastoma of the vulva in a 40-year-old female patient. We also discuss important diagnostic considerations when approaching such large tumors, particularly in the setting of a biopsy specimen.

Vulvar angiomyofibroblastoma is molecularly defined by recurrent MTG1-CYP2E1 fusions

Angiomyofibroblastoma (AMF), a rare benign vulvovaginal mesenchymal tumour, poses a diagnostic challenge due to histologic and immunohistochemical overlap with other vulvar mesenchymal tumours. Recently, MTG1-CYP2E1 fusion transcripts were reported in 5/5 AMFs; no other genetic alterations have been described to date. Herein, we sought to investigate the frequency of the MTG1-CYP2E1 fusion and the presence of other potential genetic alterations in a cohort of AMFs (n = 7, patient age range: 28-49 years). Tumours demonstrated classic morphologic features including alternating hypo/hypercellular areas, capillary channels surrounded by epithelioid/spindled tumour cells, and variable amounts of mature adipose tissue. reverse transcription-polymerase chain reaction (RT-PCR) for MTG1-CYP2E1 fusion, performed in all seven cases, showed the fusion transcript in five of six cases (one case with technical failure). Two tumours, including the one lacking the fusion, were subjected to targeted next-generation sequencing (104 genes) and a sarcoma fusion assay (28 genes); the fusion negative AMF also underwent RNA sequencing. No additional mutations, copy number alterations, or fusion genes were identified with the assays employed. We conclude that the majority of AMFs harbour recurrent MTG1-CYP2E1 fusion transcripts and identification of this fusion may aid in the diagnosis.

Practical Approach to the Diagnosis of the Vulvo-Vaginal Stromal Tumors: An Overview

Background: The category of the “stromal tumors of the lower female genital tract” encompasses a wide spectrum of lesions with variable heterogeneity, which can be nosologically classified on the basis of their morphologic and immunohistochemical profiles as deep (aggressive) angiomyxoma (DAM), cellular angiofibroma (CAF), angiomyofibroblastoma (AMFB) or myofibroblastoma (MFB). Despite the differential diagnosis between these entities being usually straightforward, their increasingly recognized unusual morphological variants, along with the overlapping morphological and immunohistochemical features among these tumours, may raise serious differential diagnostic problems. Methods and Results: The data presented in the present paper have been retrieved from the entire published literature on the PubMed website about DAM, CAF, AFMB and MFB from 1984 to 2021. The selected articles are mainly represented by small-series, and, more rarely, single-case reports with unusual clinicopathologic features. The present review focuses on the diagnostic clues of the stromal tumours of the lower female genital tract to achieve a correct classification. The main clinicopathologic features of each single entity, emphasizing their differential diagnostic clues, are discussed and summarized in tables. Representative illustrations, including the unusual morphological variants, of each single tumour are also provided. Conclusion: Awareness by pathologists of the wide morphological and immunohistochemical spectrum exhibited by these tumours is crucial to achieve correct diagnoses and to avoid confusion with reactive conditions or other benign or malignant entities.

Potential pathogenetic link between angiomyofibroblastoma and superficial myofibroblastoma in the female lower genital tract based on a novel MTG1-CYP2E1 fusion

Angiomyofibroblastoma and superficial myofibroblastoma are distinctive benign mesenchymal tumors occurring in the female lower genital tract. Despite their significant overlapping clinicopathologic features, including the presence of bland-looking spindle or oval cells with myofibroblastic or myoid differentiation, the tumors have been regarded as separate entities. Although subepithelial, hormone-sensitive mesenchymal cells of the female lower genital tract are considered as their potential common progenitor cells, their potential kinship or pathogenetic similarities remain elusive. Based on the identification of a novel RNA sequencing-based MTG1-CYP2E1 fusion transcript in an angiomyofibroblastoma index case, we investigated an additional ten samples of the tumor and its site-specific histological mimics, including eight superficial myofibroblastomas, four deep angiomyxomas, four cellular angiofibromas, three fibroepithelial stromal polyps, and eight non-site-specific mesenchymal tumors occurring in the female lower genital tract. Using reverse transcription-polymerase chain reaction, we showed that the MTG1-CYP2E1 fusion transcripts were consistently detectable in angiomyofibroblastomas (5/5, 100%) and often in superficial myofibroblastomas (3/5, 60%) but were not detected in the other examined site-specific or non-site-specific mesenchymal tumors. Our immunohistochemical experiments showed that CYP2E1, an isoenzyme belonging to the cytochrome P450 superfamily, exhibited increased positivity in tumors with MTG1-CYP2E1 than was observed in fusion-negative tumors (RR = 6.56, p = 0.001). The results of our study provide further evidence supporting the assertion that angiomyofibroblastoma and superficial myofibroblastoma represent phenotypic variants of site-specific mesenchymal tumors and share a common oncogenic mechanism.

The Wide Morphological Spectrum of Deep (Aggressive) Angiomyxoma of the Vulvo-Vaginal Region: A Clinicopathologic Study of 36 Cases, including Recurrent Tumors

Background: Deep angiomyxoma (DAM) is currently included in the category of “specific stromal tumors of the lower female genital tract”, along with angiomyofibroblastoma, cellular angiofibroma and myofibroblastoma. Given the high rate of local recurrences, it is crucial to recognize DAM from other tumors that possess indolent behaviour. In the present paper, we analyzed the morphological and immunohistochemical features of 42 surgically-resected vulvo-vaginal DAMs (36 primary and 6 recurrent lesions) in order to widen the morphological spectrum of this uncommon tumor. Methods: A series of 36 cases of surgically-resected primary vulvo-vaginal DAMs were retrospectively collected. Locally recurrent tumors were also available for six of these cases. Results: Out of the primary tumors, 25 out of 36 exhibited the classic-type morphology of DAM. In the remaining cases (11/36 cases), the following uncommon features, which sometimes coexist with one another, were observed: (i) alternating myxoid and collagenized/fibrous areas; (ii) hypercellular areas; (iii) neurofibroma-like appearance; (iv) perivascular hyalinization; (v) microcystic/reticular stromal changes; (vi) “microvascular growth pattern”; (vii) perivascular cuffing; (viii) nodular leiomyomatous differentiation; (ix) hypocellular and fibro-sclerotic stroma. Among the six locally recurrent tumors the following features were observed: (i) classic-type morphology; (ii) hypocellular fibro-sclerotic stroma; (iii) extensive perivascular hyalinization, lumen obliteration and formation of confluent nodular sclerotic masses; (iv) hypercellularity. Immunohistochemically, the neoplastic cells of classic-type DAM in both primary and recurrent tumors were diffusely stained with desmin, suggesting a myofibroblastic nature; in contrast, the neoplastic cells showing elongated fibroblastic-like morphology and set in collagenized/fibrosclerotic stroma in both primary and recurrent tumors were negative or only focally stained with desmin, which is consistent with a fibroblastic profile. Conclusion: Although diagnosis of DAM is usually straightforward if typical morphology is encountered, diagnostic problems may arise when a pathologist is dealing with unusual morphological features, especially hypercellularity, extensive collagenous/fibrosclerotic stroma or neurofibroma-like appearance.

Mesenchymal lesions of the vulva

Mesenchymal lesions of the vulva include site-specific entities limited to the lower genital tract, as well as a range of non-site-specific tumors that are more common at extragenital sites. Site-specific lesions include fibroepithelial stromal polyp, cellular angiofibroma, angiomyofibroblastoma, and aggressive angiomyxoma. Non-site-specific tumors that may occur in the vulva include those of smooth muscle, skeletal muscle, vascular, neural, adipocytic, and uncertain differentiation. This review discusses both site-specific and non-site-specific vulvar mesenchymal lesions including non-neoplastic proliferations, benign neoplasms, locally aggressive neoplasms with a predilection for local recurrence, neoplasms of indeterminate biologic potential, and frankly malignant neoplasms with a high risk of distant metastasis and death. Accurate diagnosis is essential for proper management, and is facilitated by correlation with clinical findings and targeted application of immunohistochemical and molecular studies.

Cytogenetics of Spindle Cell/Pleomorphic Lipomas: Karyotyping and FISH Analysis of 31 Tumors

BACKGROUND

Spindle cell/pleomorphic lipomas are benign tumors. Here, we present our cytogenetic data on 31 such tumors.

MATERIALS AND METHODS

G-banding chromosome analysis and (in selected cases) fluorescence in situ hybridization (FISH) using probes for FOXO1, RB1, and HMGA2 were performed.

RESULTS

Rearrangements of chromosome 13 were found in 58% of tumors. Chromosomes 6, 1, 12, and 11 were also involved in 42%, 26%, 26%, and 23% of tumors, respectively. FISH analysis showed heterozygous deletion of RB1 in seven samples with chromosome 13 aberrations. In four of them, FOXO1 was also deleted. In two tumors with 12q15 rearrangements, FISH confirmed that HMGA2 was targeted.

CONCLUSION

Structural rearrangements of 13q or losses of an entire chromosome 13 are the most common cytogenetic aberrations in spindle cell/pleomorphic lipomas. However, cytogenetic variation exists similarly to what is found in other lipomas, suggesting that various pathways may be responsible for tumorigenesis.

Fibroepithelial Stromal Polyp of the Vulva: Case Report and Review of Potential Histologic Mimickers

Vulvar tumors arising from submucosal connective tissue, some of which exhibit hormonal responsiveness, have many clinical and histologic overlapping characteristics. We present a case of a fibroepithelial stromal polyp arising from the vulva of a 22-year-old female. We review the differential diagnosis with an emphasis on distinguishing features of these uncommon neoplasms. Accurate diagnosis is essential as the extent of surgical resection and risk of local recurrence varies for these tumors.

A Vaginal Angiomyofibroblastoma as a Rare Cause of a Prolapsing Vaginal Mass: A Case Report and Review of the Literature

Introduction

Angiomyofibroblastoma (AMFB) is a rare, benign, mesenchymal cell tumour which presents as a slow-growing mass. It is most commonly seen in the vulva and is often mistaken for Bartholin's abscess. It is histologically diagnosed by the presence of stromal cells intermingled with small blood vessels. It is morphologically similar to cellular angiofibroma and aggressive angiomyxoma, the latter of which is locally invasive and has a possibility of metastasis and a high risk of local recurrence. There is one reported case of an AMFB undergoing sarcomatous transformation.

Case Report

We report a case of a multiparous, 36-year-old woman with an anterior vaginal mass which was inappropriately treated as a vaginal prolapse prior to definitive surgical management. This is only the second reported case of an AMFB presenting as a prolapsing mass.

Lipomatous angiomyofibroblastoma of the vulva: A case report and review of the literature

Lipomatous angiomyofibroblastoma is extremely rare, with only 16 cases reported to date. We herein describe an additional case arising in the left vulvar region of a 49-year-old woman. The resected 5.3-cm yellowish tumor predominantly consisted of fat cells (85% of the tumor), together with medium- and small-sized vessels, multifocal fibrotic areas and pseudoangiomatous spaces. Spindle, rounded, and/or epithelioid tumor cells proliferated in a nest and/or cord-like pattern, or singly within perivascular fibrous tissues and between fat cells. The tumor cells were positive for vimentin, estrogen receptor, progesterone receptor, B-cell lymphoma 2, and CD10, but were negative for desmin, cytokeratin, epithelial membrane antigen, S-100 protein, human melanoma black 45, C-kit and p40. Ultrastructural examination revealed that these tumor cells exhibited fibroblastic characteristics. Lipomatous angiomyofibroblastoma should be discriminated from other lipomatous tumors, including spindle cell lipoma, angiomyolipoma and cellular angiofibroma containing numerous fat cells.

Cellular angiofibroma of the vulva: a poorly known entity, a case report and literature review

BACKGROUND

Cellular angiofibroma represents a newly described, site specific tumor. Histologically, CAF is a benign mesenchymal neoplasm characterized by two principal components: bland spindle cells and prominent small to medium-sized vessels with mural hyalinization. The indolent nature of the lesion is underscored by the uniformity of its constituent stromal cells, and their lack of nuclear atypia. Characterization by immunohistochemistry is helpful distinguishing Cellular angiofibroma from other mesenchymal lesions.

CASE PRESENTATION

We report the case of a 37-year-old woman, presenting with a painless nodule involving the vulva. This lesion had gradually increased in size; a simple excision was performed, and follow up was unremarkable. Gross examination showed a well circumscribed, firm tumor measuring 3× 3 × 2,5 cm. Histologically, the tumor was composed of uniform, short spindle-shaped cells, proliferating in an edematous to fibrous stroma and numerous small to medium-sized thick-walled vessels. A panel of immunohistochemical stains was performed, and confirmed the diagnosis of Cellular angiofibroma.

CONCLUSION

In this report we aim to describe the clinical, pathological and immunohistochemical features of this rare entity through a literature review, and to discuss other vulvar mesenchymal lesions.

Genital soft tissue tumors

Mesenchymal neoplasms of the vulvovaginal and inguinoscrotal regions are among the most diagnostically challenging specimens in the pathology laboratory owing largely to their unique intersection between general soft tissue tumors and relatively genital-specific mesenchymal tumors. Genital stromal tumors are a unique subset of soft tissue tumors encountered at this location, and this group includes fibroepithelial stromal polyp, superficial (cervicovaginal) myofibroblastoma, cellular angiofibroma, mammary-type myofibroblastoma, angiomyofibroblastoma and aggressive angiomyxoma. Aside from the striking morphologic and immunophenotypic similarity that is seen with these entities, there is evidence that a subset of genital stromal tumors may be linked genetically. This review will focus on simplifying this group of tumors and provide the pathologist or dermatopathologist with practical management information. Smooth muscle tumors of the external genitalia will also be discussed.

Spindle Cell Epithelioma of the Vagina

Spindle cell epitheliomas of the vagina are rare benign tumors of uncertain histogenesis. It has been hypothesized that they originate from a pluripotent cell population. Here, we report 2 cases of spindle cell epitheliomas of the vagina. Both patients presented with a painless vaginal nodule. The resected lesions were solid, well circumscribed, and composed of a proliferation of epithelioid or epithelial cells admixed with spindle cells without atypia. The 2 cellular populations expressed epithelial and mesenchymal markers. Based on these morphologic and immunohistochemical findings, a diagnosis of spindle cell epithelioma was rendered in both cases. Furthermore, we describe for the first time the expression of WT-1 (Wilms’ tumor protein 1) and calretinin in addition to the previously defined immunohistochemical profile.

Immunohistochemistry as potential diagnostic pitfall in the most common solid tumors of children and adolescents

Making a correct diagnosis when dealing with a small round blue cell tumor (SRBCT) of children and adolescents may be relatively straightforward if the tumor arises in the typical clinical setting and the classic pathologic features are all recognizable. However it is widely known that diagnostic difficulties may arise because of: (i) many tumors share overlapping morphological and/or immunohistochemical features; (ii) considerable clinical, pathologic, and immunohistochemical variations do exist; (iii) the increasing use of small biopsies in daily practice makes the diagnosis of these neoplasms more challenging. Accordingly, immunohistochemical analyses are currently mandatory in establishing the correct diagnosis. In this regard there is the need to identify more sensitive and specific immunomarkers useful in the distinction of the several tumor entities. Over the last decades, several markers, such as CD99, WT1 protein, desmin, myogenin, NB84, and INI1 have been identified, providing a considerable help in recognition of the most common solid tumors (ESW/pPNET, rhabdomyosarcoma, neuroblastoma, Wilms' tumor, desmoplastic small round cell tumor; malignant rhabdoid tumor) in children and adolescents. However, at the same time, their unusual, unexpected expression can result in a misinterpretation of the immunohistochemical results, especially by pathologists who are not familiar with oncologic pediatric pathology. Therefore the present review focuses on the potential immunohistochemical pitfalls which should be kept in mind by pathologists to prevent diagnostic errors when dealing with SRBCTs.