Inflammatory myofibroblastic tumor of the uterus with prominent myxoid change

Advances in uterine inflammatory myofibroblastic tumours: Diagnostic challenges and risk stratification

The current understanding of inflammatory myofibroblastic tumours (IMTs) of the gynaecological tract has recently been enhanced by their increased recognition. This increase is largely due to greater accessibility to RNA-based molecular assays used to identify their defining ALK rearrangements. This review summarises the clinical characteristics, morphological spectrum, immunohistochemical profile and molecular underpinnings of uterine IMT. Additionally, this review discusses practical diagnostic considerations including overlap between uterine IMT and smooth muscle tumours as well as pregnancy-associated uterine IMT. Finally, we highlight recent literature demonstrating the potential for aggressive behaviour in uterine IMT, including a novel risk stratification model for identifying high-risk IMT.

Uterine inflammatory myofibroblastic tumor harboring novel NUDCD3-ROS1 and NRP2-ALK fusions: clinicopathologic features of 4 cases and literature review

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm of intermediate biologic potential, which occurs mostly in the lung and abdomen cavity of children and young adults. Uterine IMTs are rare. Herein, we presented clinicopathologic features of 4 uterine IMTs. All four patients were initially diagnosed as leiomyosarcoma by other hospitals and corrected to uterine IMT after pathological consultation. Patient age ranged from 44 to 64 years old. Two cases demonstrated multiple masses. Microscopically, three tumors were composed of fascicular spindled cells with eosinophilic cytoplasm, and the other one was densely composed of spindled and epithelioid cells with bizarre and multinucleated cells. Tumor cells showed variable nuclear atypia, ranging from mild to severe. Prominent inflammatory cell infiltration was found in one case, and necrosis in two tumors. Immunochemistry staining revealed expression of smooth muscle markers in all four tumors, including a-SMA and desmin. Three tumors were positive for ALK protein expression. FISH analysis demonstrated ROS1 rearrangement in one tumor and ALK rearrangement in the other 3 tumors. NGS analysis showed novel NUDCD3-ROS1 and NRP2-ALK fusions in two tumors and TNS1-ALK fusion in the other two tumors. Gene aberrations involving p53 signaling pathway were identified in all four cases. All patients received surgery as primary treatment, and one had neoadjuvant chemotherapy. Three patients recurred within 12 months, and the other one recurred after 7 years. Patients with recurrence were treated with a combination of chemotherapy, targeted therapy, or surgery. In conclusion, the diagnosis of uterine IMTs can be challenging. Ancillary studies including ALK IHC, FISH, and NGS are helpful to establish diagnosis and to discover novel gene rearrangement potentially for targeted therapy.

Uterine Inflammatory Myofibroblastic Tumors: Proposed Risk Stratification Model Using Integrated Clinicopathologic and Molecular Analysis

Inflammatory myofibroblastic tumor (IMT) of the uterus is a rare mesenchymal tumor with largely benign behavior; however, a small subset demonstrate aggressive behavior. While clinicopathologic features have been previously associated with aggressive behavior, these reports are based on small series, and these features are imperfect predictors of clinical behavior. IMTs are most commonly driven by ALK fusions, with additional pathogenic molecular alterations being reported only in rare examples of extrauterine IMTs. In this study, a series of 11 uterine IMTs, 5 of which demonstrated aggressive behavior, were evaluated for clinicopathologic variables and additionally subjected to capture-based next-generation sequencing with or without whole-transcriptome RNA sequencing. In the 6 IMTs without aggressive behavior, ALK fusions were the sole pathogenic alteration. In contrast, all 5 aggressive IMTs harbored pathogenic molecular alterations and numerous copy number changes in addition to ALK fusions, with the majority of the additional alterations present in the primary tumors. We combined our series with cases previously reported in the literature and performed statistical analyses to propose a novel clinicopathologic risk stratification score assigning 1 point each for: age above 45 years, size≥5 cm,≥4 mitotic figures per 10 high-power field, and infiltrative borders. No tumors with 0 points had an aggressive outcome, while 21% of tumors with 1 to 2 points and all tumors with ≥3 points had aggressive outcomes. We propose a 2-step classification model that first uses the clinicopathologic risk stratification score to identify low-risk and high-risk tumors, and recommend molecular testing to further classify intermediate-risk tumors.

Uterine inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is recognized as a true neoplasm of unknown etiology, but its pathogenesis is related to abnormalities in the ALK gene. This is an uncommon tumor with a wide anatomic distribution and often constitutes a challenging diagnosis owing to its histological similarities with other tumors. Uterine IMTs are rare and their detailed characteristics should be described based on case reports and small case series. Thus, we performed a comprehensive review of the literature showing that uterine IMTs show a wide range of age at diagnosis (median, 39 years), and a symptomatology similar to that of common leiomyomas, only rarely presenting with inflammatory manifestations. IMTs represent 0.1% of "leiomyomas," an estimate that increases to 10% for pregnant women and to 14% for the smooth muscle tumors of uncertain malignant potential (STUMP) category of tumors, implying that tumors excised during pregnancy, STUMPs, and leiomyosarcomas should be systematically screened with ALK immunohistochemistry, as this is a targetable abnormality. Most reported cases are ALK-positive; the fusion partners vary, but in pregnancy-associated tumors, TIMP3 prevails. Almost 25% of the patients will show an aggressive course, and this is associated with older age, non-pregnancy-associated tumors, larger tumors, infiltrative tumor border, absence of abundant inflammation, atypia, important mitotic activity, and necrosis.

Inflammatory myofibroblastic tumour of an unusual presentation in the uterine cervix: a case report

Background

Inflammatory myofibroblastic tumour is an infrequent mesenchymal neoplasia of unknown aetiology and variable behaviour, ranging from rather benign lesions to locally aggressive and even metastatic disease. Its presence has been described in almost all organs; however, its location in the female genital tract has rarely been reported.

Case presentation

We present the case of a 47-year-old female, who was studied in our institution for a recent medical history of several weeks of dyspareunia and abdominal pain. She underwent pertinent studies including ultrasonography and CT scan. Under suspicion of degenerated leiomyoma, a total hysterectomy was performed. Unexpectedly, the pathological study of the surgical specimen showed very few tumour cells with focal fusiform morphology surrounded by an abundant inflammatory infiltrate; a thorough immunohistochemistry study lead to myofibroblastic tumour of the cervix diagnosis. A PET-CT scan did not show metastatic disease. The patient did not undergo any adjuvant treatment, and she is currently on surveillance with no evidence of disease relapse.

Conclusions

Inflammatory myofibroblastic tumour remains a rare entity yet to be fully elucidated. The diagnosis is based on pathological study due to the lack of typical clinical manifestations and typical radiological images. Surgical resection is the most frequent treatment, whereas chemotherapy and radiotherapy are restricted to locally advanced or metastatic disease. Tirosine kinase inhibitor crizotinib has shown promising results especially in tumours harbouring ALK mutation.

[Immunohistochemical and molecular diagnosis of inflammatory myofibroblastic tumor of the uterus: a literature review and a clinical case]

Inflammatory myofibroblastic tumors of the uterus (uIMT) are rare and difficult to diagnose neoplasms, since the morphological characteristics of this tumor are not specific and are found in other pathological changes. In addition, until recently, specific uIMT markers have not been identified and their diagnostic standards not defined. However, in recent years, there have been more and more studies aimed to identify characteristic morphological, immunohistochemical, and molecular genetic features for the differential diagnosis of uIMT. Recent papers studying uIMT indicate anaplastic lymphoma kinase (ALK) as a potentially reliable marker of uIMT. This communication describes a clinical case of uIMT in a 40-year-old woman who has been preoperatively diagnosed with a large subserous interstitial myomatous nodule. The final diagnosis was made, by analysing a combination of morphological and immunohistochemical signs. This clinical case with a literature review is indicated to consider ALK as a key criterion in the diagnosis of uIMT, as well as the relationship between subsequent treatment and the presence of ALK in the studied tissues.

Uterine Inflammatory Myofibroblastic Neoplasms With Aggressive Behavior, Including an Epithelioid Inflammatory Myofibroblastic Sarcoma: A Clinicopathologic Study of 9 Cases

The experience with uterine inflammatory myofibroblastic neoplasms with an unfavorable outcome is limited. We present the clinicopathologic features of 9 such cases, including 8 inflammatory myofibroblastic tumors (IMTs) and 1 epithelioid inflammatory myofibroblastic sarcoma (EIMS). Median patient age for the IMT group was 50.5 years; the patient with EIMS was 43 years old. Patients presented with abnormal uterine bleeding, presumed fibroids, pelvic pain, arthralgia and low-grade fever, as well as an incidental finding. Median tumor size for the IMTs was 8.5 cm. The borders were either infiltrative or well-circumscribed. Histologically, IMTs were purely fascicular or myxoid or showed predominance of one or the other pattern. Seven tumors were spindled, and 1 was both spindled and epithelioid. Tumors had variable nuclear atypia, ranging from grade 1 to 3. All tumors had an inflammatory infiltrate-predominantly lymphocytic, majority had necrosis (62.5%) and none had lymphovascular invasion. 7/8 (87.5%) tumors were positive for ALK-1 by immunohistochemistry (IHC). One tumor was negative for ALK-1 by IHC but was positive for ALK fusion by fluorescence in situ hybridization and had TNS1-ALK fusion by next-generation sequencing (NGS). Three other tumors with NGS testing showed one of the following ALK-fusion partners: FN1, DCTN1, and IGFBP5. The EIMS had infiltrative borders, myxoid and hyalinized patterns, epithelioid cells, and no lymphovascular invasion. This tumor was ALK-1 positive by IHC, had ALK rearrangement by fluorescence in situ hybridization and RANBP2-ALK fusion by NGS. Extrauterine disease at time of diagnosis was noted in 2/8 (25%) of IMTs, and in the single case of EIMS. Seven patients had surgery as primary treatment, 1 patient had neoadjuvant chemotherapy and 1 patient declined treatment. Patients with recurrence were treated with a combination of chemotherapy, targeted therapy, radiotherapy or hormonal therapy. Most patients (71.4%) recurred within 24 months (mos). Two thirds of patients were alive with disease at last follow up (mean 43.6 mos). The patient with EIMS was alive with disease at 22 mos. IMT referral cases were initially diagnosed as smooth muscle tumors in 87.5% of cases; while the EIMS was diagnosed as high-grade endometrial stromal sarcoma. Lack of consideration of IMT in the differential diagnosis of smooth muscle tumors with myxoid features can result in misdiagnosis and under-utilization of targeted therapy in these patients.

ALK Immunohistochemistry and Molecular Analysis in Uterine Inflammatory Myofibroblastic Tumor: Proceedings of the ISGyP Companion Society Session at the 2020 USCAP Annual Meeting

Inflammatory myofibroblastic tumor of the uterus (uIMT) is rare. However, it has been increasingly recognized in recent years, largely due to more awareness of its occurrence in the gynecologic tract and the characterization of features that help distinguish it from more common lesions in the differential diagnosis, particularly smooth muscle neoplasms. One of these features is expression of anaplastic lymphoma kinase (ALK, also known as CD246), which has been documented in most uIMTs described in the literature. This review concentrates on the role of ALK testing in the diagnosis and management of uIMT. In terms of immunohistochemistry, an emphasis on antibody selection, sensitivity/specificity, interpretation and quality control is given. Regarding molecular analysis for ALK alterations, this review appraises fluorescence in situ hybridization and RNA sequencing technologies. Lastly, the role of tyrosine kinase inhibitor therapy in patients with uIMT is discussed, highlighting the importance of a correct diagnosis of this entity.

Recent advances in smooth muscle tumors with PGR and PLAG1 gene fusions and myofibroblastic uterine neoplasms

Uterine epithelioid and myxoid leiomyosarcomas and inflammatory myofibroblastic tumors are rare mesenchymal neoplasms. Next-generation sequencing recently detected novel PGR fusions in uterine epithelioid leiomyosarcomas that demonstrate characteristic rhabdoid and spindled morphology. PLAG1 gene fusions have also been identified in a subset of myxoid leiomyosarcomas and are associated with PLAG1 overexpression. ALK rearrangements underpin the vast majority of uterine inflammatory myofibroblastic tumors, which demonstrate morphologic, and immunohistochemical features similar to those of inflammatory myofibroblastic tumors elsewhere. This review summarizes the morphologic, immunophenotypic, and molecular genetic features of PGR fusion-positive epithelioid leiomyosarcoma, PLAG1 fusion-positive myxoid leiomyosarcoma, and inflammatory myofibroblastic tumors of the uterus.

Inflammatory Myofibroblastic Tumor in Female Genital Tract

CONTEXT.—

Inflammatory myofibroblastic tumor is a mesenchymal neoplasm of low malignant potential. It was first described in lung, but is known to occur in many extrapulmonary sites including female genital organs, most commonly the uterus. It has a high recurrence rate and a low risk for metastasis. A more recently described aggressive variant, epithelioid myofibroblastic sarcoma with a predilection for the abdominal cavity of males, has also been recently reported to occur in the ovary. This tumor is composed of spindled and epithelioid myofibroblasts in a variably myxoid stroma and commonly shows a fascicular growth pattern with positive staining for desmin, smooth muscle actin, and CD10, which may mimic a smooth muscle or endometrial stromal neoplasm. In the female genital tract it has the potential for being misdiagnosed as a leiomyoma, endometrial stromal tumor, or as a myxoid leiomyosarcoma, resulting in undertreatment or overtreatment. It harbors rearrangements in the ALK gene, resulting in abnormal expression of ALK protein. Immunostaining for ALK is a helpful diagnostic tool.

OBJECTIVE.—

To provide a brief review of clinical, histologic, immunohistochemical, and molecular features of inflammatory myofibroblastic tumor with emphasis on possible diagnostic pitfalls in the female genital tract.

DATA SOURCES.—

Review of pertinent literature on inflammatory myofibroblastic tumor occurring in the female genital tract and personal experience of the authors.

CONCLUSIONS.—

Inflammatory myofibroblastic tumor in the female genital tract can mimic other more common benign and malignant tumors like leiomyoma, leiomyosarcoma, and endometrial stromal sarcoma. Familiarity with clinical and histologic features and use of ALK immunostaining can be critical for correct diagnosis.

Uterine inflammatory myofibroblastic tumor: more common than expected: Case report and review

RATIONALE

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal neoplasm composed of spindled to epithelioid cells with prominent myxoid stroma and inflammatory infiltrate. It has a low but definite malignant potential. However, its management has never been standardized.

PATIENT CONCERNS AND DIAGNOSIS

We present the first case of uterine IMT laparoscopically treated. Moreover, we reviewed the English literature regarding uterine IMT published between 1987 and June 2017. A total of 72 cases of uterine IMT were included. Clinical and pathological characteristics, treatments and outcomes were recorded.

INTERVENTIONS AND OUTCOMES

A total laparoscopic hysterectomy with opportunistic bilateral salpingectomy was performed. Patient is free of disease at 6 months of follow-up.

LESSONS

Uterine IMT may be identified by anaplastic lymphoma kinase overexpression, its prognosis is usually good, complete excision seems to be effective to avoid relapse and mini invasive surgery seems to be effective and safe to treat uterine IMT. However, considering the age of women affected by disease, conservative management, or medical therapy could be taken in account to avoid surgical injuries and to preserve fertility.

Inflammatory Myofibroblastic Tumors of the Female Genital Tract Are Under-recognized: A Low Threshold for ALK Immunohistochemistry Is Required

Inflammatory myofibroblastic tumor (IMT) of the female genital tract is under-recognized. We investigated the prevalence of ALK-positive IMT in lesions previously diagnosed as gynecologic smooth muscle tumors. Immunohistochemistry (IHC) for ALK was performed on tissue microarrays of unselected tumors resected from 2009 to 2013. Three of 1176 (0.26%) “leiomyomas” and 1 of 44 (2.3%) “leiomyosarcomas” were ALK IHC positive, confirmed translocated by fluorescence in situ hybridization (FISH) and therefore more appropriately classified as IMT. On review significant areas of all 4 tumors closely mimicked smooth muscle tumors morphologically, but all showed at least subtle/focal features suggesting IMT. Recognizing that the distinction between IMT and leiomyoma/leiomyosarcoma can be subtle, we then reviewed 1 hematoxylin and eosin slide from each patient undergoing surgery for “leiomyoma” from 2014 to 2017 and selected cases for ALK IHC with a low threshold. Of these, 30 of 571 (5.3%) underwent IHC. Two were confirmed to be IHC positive and FISH rearranged. Of the 6 IMTs, only 1 tumor with a previous diagnosis of leiomyosarcoma, an infiltrative margin and equivocal necrosis, metastasized. Of note it demonstrated a less aggressive clinical course compared with most metastatic leiomyosarcomas (alive with disease at 6 y). The patient was subsequently offered crizotinib to which she responded rapidly. In conclusion, IMTs may closely mimic gynecologic smooth muscle tumors. IMTs account for at least 5 of 1747 (0.3%) tumors previously diagnosed as leiomyoma and 1 of 44 (2.3%) as leiomyosarcoma. These tumors may be recognized prospectively with awareness of subtle/focal histologic clues, coupled with a low threshold for ALK IHC.

Inflammatory myofibroblastic tumor of the uterus: a clinicopathological, immunohistochemical, and molecular analysis of 13 cases highlighting their broad morphologic spectrum

Inflammatory myofibroblastic tumors of the uterus are rare, and although most have a favorable prognosis, a small subset exhibit extrauterine disease, recur, or cause death. In this study, we evaluated the morphology and immunoprofile of 13 uterine inflammatory myofibroblastic tumors, including four with aggressive behavior. ALK rearrangements were detected by fluorescence in situ hybridization and fusion partners by anchored multiplex assay. Patients ranged from 8 to 63 (mean 39) years and tumors from 2.5 to 20 (mean 7.4) cm. Myxoid, compact, and hyalinized patterns were noted in 13, 12, and 2 tumors, ranging from 1 to 100%, 5 to 99%, and 0 to 5%, respectively. Nuclear atypia was mild in six (46%), moderate in five (38%), and severe in two (15%), with ganglion-like cells in two tumors. Mitoses ranged from 0 to 24 (mean 5) per 10 high-power fields. Inflammation was mild in five (38%), moderate in three (23%), and marked in five (38%), consisting of a lymphoplasmacytic infiltrate that was lymphocyte-predominant in six (46%). Lymphovascular invasion was noted in two (15%) and necrosis in eight (62%). All but one tumor were ALK-positive by immunohistochemistry, with granular cytoplasmic staining in nine (82%). ALK rearrangements (tested in 10) were detected in eight and was absent in one. The remaining tumor showed an isolated green 5' ALK signal. Fusion partners were identified in 10 (77%) and included THBS1 (n=3), IGFBP5 (n=2), DES (n=2), SEC31 (n=1), TPM3 (n=1), and TIMP3 (n=1). Size ≥8 cm was predictive of aggressive behavior (P<0.01), with increased mitoses (≥7 per 10 high-power fields), lymphovascular invasion, and compact-predominance approaching statistical significance. These data show that inflammatory myofibroblastic tumors of the uterus are morphologically heterogenous with frequent ALK expression and a variety of ALK fusion partners. Recognition of this rare mesenchymal neoplasm is crucial as those with aggressive behavior can potentially be treated with tyrosine kinase inhibitors.

Uterine Inflammatory Myofibroblastic Tumors Frequently Harbor ALK Fusions With IGFBP5 and THBS1

Inflammatory myofibroblastic tumor (IMT) can occur in a number of anatomic sites, including the uterus. Like its soft tissue counterpart, uterine IMT frequently expresses ALK and harbors ALK genetic rearrangements. The aim of this study is to fully characterize the genetic fusions that occur in uterine IMT. We studied 11 uterine IMTs with typical histology and 8 uterine myxoid smooth muscle tumors (5 leiomyomas, 1 smooth muscle tumor of uncertain malignant potential, and 2 leiomyosarcomas) in which the differential of IMT was considered, using a RNA-sequencing-based fusion assay to detect genetic fusions involving ALK, ROS1, RET, NTRK1/3, and other genes. ALK was expressed in 10 of 11 IMTs and 1 tumor initially categorized as a myxoid leiomyoma (granular cytoplasmic staining with paranuclear accentuation). Fusion transcripts involving ALK were identified in 9 of 10 ALK immunopositive IMTs, with 3 harboring IGFBP5-ALK, 3 harboring THBS1-ALK, 2 harboring FN1-ALK, and 1 harboring TIMP3-ALK. Among the smooth muscle tumors, IGFBP5-ALK fusion transcript was identified in only 1 ALK immunopositive case. Further review revealed that although a diagnosis of IMT was considered for the ALK immunopositive myxoid leiomyoma, this diagnosis was not initially rendered only because fluorescence in situ hybridization analysis was interpreted as negative for ALK genetic rearrangement; this case is best reclassified as an IMT. Notably, all the ALK fusions identified in our study included the transmembrane domain-encoding exon 19 of ALK. Our findings confirm the high frequency of ALK fusions in uterine IMT, with an enrichment of novel 5' ALK fusion partners (IGFBP5, THBS1, and TIMP3) and exon 19-containing ALK fusion. Given that IGFBP5 and FN1 are both situated on the same chromosome as ALK, fluorescence in situ hybridization analysis for ALK rearrangement may not be reliable and a negative result should not exclude a diagnosis of uterine IMT if the histologic features and ALK immunostaining findings are supportive.

Giant Cell Tumor of the Uterus: A Report of 3 Cases With a Spectrum of Morphologic Features

Giant cell tumors, a well-recognized neoplasm of bone, can rarely be found in the uterus. Such tumors are characterized by a dual population of mononuclear and osteoclast-like giant cells that lack epithelial and specific mesenchymal differentiation. In this study, the clinicopathologic features of 3 giant cell tumors of the uterus were reviewed. Immunohistochemistry for CD68, CD163, h-caldesmon, desmin, SMA, AE1/AE3, CD10, ER, PR, cyclin D1, CD1a, CD34, CD30, S100, myogenin/myoglobin, and Ki-67 was performed in all tumors, along with ultrastructural analysis in one. The patients were 47, 57, and 59 yr and the tumors measured 2.5, 7.5, and 16.0 cm. One neoplasm was confined to the endometrium, whereas the other 2 were myometrial. All 3 tumors showed a nodular growth comprised of mononuclear and osteoclast-like giant cells. The endometrial-confined tumor consisted of histologically benign mononuclear cells, whereas the others exhibited marked atypia. Mitotic activity was up to 5/10 HPF in the benign tumor and up to 22/10 HPF in the malignant. No cytologic atypia or mitoses were observed in the giant cells. CD68 and CD10 were strongly and diffusely expressed in both components of 3 and 2 neoplasms, respectively. Cyclin D1 was focal in the mononuclear cells and focal to diffuse in the giant cells. CD163 was diffuse in the mononuclear cells, but absent to focal in the giant cells. Ultrastructural analysis lacked diagnostic features of epithelial or specific mesenchymal differentiation. Both malignant tumors demonstrated an aggressive behavior. In summary, although rare, giant cell tumor of the uterus should be included in the differential diagnosis of benign or malignant tumors containing osteoclast-like giant cells.

Follow-Up Imaging of Inflammatory Myofibroblastic Tumor of the Uterus and Its Spontaneous Regression

Inflammatory myofibroblastic tumor (IMT) is an aggressive benign mass that may arise from various tissues and organs with a great variability of histological and clinical appearances. Due to variable and nonspecific imaging findings, diagnosis of IMT is not obtained before surgery. The aim of this paper is to present CT and MRI findings during four-year follow-up of complete, spontaneous regression of IMT of the uterus. The diagnosis was made by histology and immunohistochemistry analysis of the open excisional biopsy specimen. At that time, the organ of origin was not specified. After analysis of the follow-up imaging findings and the mode of tumor regression, the uterus was proclaimed as the probable site of origin. IMT of the uterus is extremely rare and has been reported in ten cases up to now. The gradual, complete regression of uterine IMT documented by CT and MRI may contribute to understanding of its nature.

Inflammatory myofibroblastic tumor of the uterus: clinical and pathologic review of 10 cases including a subset with aggressive clinical course

Inflammatory myofibroblastic tumor is currently regarded as a neoplasm with intermediate biological potential and a wide anatomic distribution. Inflammatory myofibroblastic tumors of the female genital tract are rare, and to date reported cases behaved indolently. We describe, herein, 10 cases of uterine inflammatory myofibroblastic tumor, 3 of which had an aggressive clinical course. Subject age ranged from 29 to 73 years. Tumors were composed of spindle and epithelioid myofibroblastic cells admixed with lymphoplasmacytic infiltrates in a variably myxoid stroma. Two growth patterns, myxoid and fascicular (leiomyoma-like), were noted. All tumors were positive for ALK expression by immunohistochemistry, which was stronger in the myxoid areas. Smooth muscle marker and CD10 expression was variable in extent, but typically positive. Fluorescence in situ hybridization for ALK rearrangements was positive in both fascicular and myxoid areas in all 8 cases tested. Three subjects showed clinical evidence of tumor aggressiveness as defined by extrauterine spread, local recurrence, or distant metastasis. Aggressive tumors were larger, had a higher proportion of myxoid stroma, and higher mitotic activity than indolent tumors. Tumor cell necrosis was seen only in cases with adverse outcome. This is the first report to describe aggressive biological behavior in uterine inflammatory myofibroblastic tumor. This diagnosis is often underappreciated and merits inclusion in the differential diagnosis of myxoid mesenchymal lesions of the uterus, particularly because patients with an aggressive course may benefit from targeted therapy.

Use of immunohistochemistry in the diagnosis of miscellaneous and metastatic tumors of the uterine corpus and cervix

Uncommon tumors in the uterus present diagnostic challenges. In some cases, the tumor subtype is usually seen outside the gynecologic tract and the possibility of a uterine primary is not considered. In other cases, histologic overlap with more common uterine tumors leads to potential misdiagnosis. Finally, metastatic carcinoma may involve the uterus and cervix. Rarely, symptoms related to the uterine metastasis may precede diagnosis of an extrauterine primary. Without the proper clinical context, the possibility of a missed diagnosis is increased. One must first be aware of these possibilities, but immunoperoxidase studies are often necessary to confirm the diagnosis. In this review, unusual and metastatic tumors involving the uterine corpus and cervix and immunoperoxidase studies used to diagnosis such tumors are discussed.

Extrauterine inflammatory myofibroblastic tumor: A case report

•This is the first case report of inflammatory myofibroblastic tumor in the literature to present with extrauterine disease.•A prompt work-up of symptoms may have precluded a tumor debulking procedure.

ALK-1 Protein Expression and ALK Gene Rearrangements Aid in the Diagnosis of Inflammatory Myofibroblastic Tumors of the Female Genital Tract

Context.—Inflammatory myofibroblastic tumor is a predominantly benign, spindle cell, mesenchymal neoplasm with myxoid areas that occurs rarely in the female genital tract and may be confused with other spindle cell lesions, particularly leiomyosarcoma.

Objective.—To investigate the utility of detecting anaplastic lymphoma kinase-1 protein expression and ALK gene rearrangements in the diagnosis of inflammatory myofibroblastic tumors in the female genital tract.

Design.—Eight inflammatory myofibroblastic tumors arising in the female genital tract and seen in consultation (from 2004 to 2011) were reviewed. Immunohistochemistry for anaplastic lymphoma kinase-1 and fluorescence in-situ hybridization studies for ALK gene rearrangements were performed.

Results.—The anatomic sites included myometrium (4 cases) and endometrium, fallopian tube, cervix, and a cervical polyp (1 each), with a patient age range from 25 to 52 years. Histologic features ranged from bland spindle cells to striking cytologic atypia, embedded in a prominent myxoid background. Anaplastic lymphoma kinase-1 immunohistochemistry was positive in 7 cases. Fluorescence in-situ hybridization studies detected ALK gene rearrangements in 5 cases. Five cases had both immunopositivity and fluorescence in-situ hybridization abnormalities, 2 cases had immunopositivity only, and 1 case was negative by both methods.

Conclusions.—This is the first report, to our knowledge, of ALK gene rearrangements in inflammatory myofibroblastic tumors in the female genital tract. If a myxoid background is appreciated in a spindle cell lesion of the female genital tract, especially if inflammatory cells are present, anaplastic lymphoma kinase-1 staining along with fluorescence in situ hybridization studies, for ALK gene rearrangements, may aid in distinguishing inflammatory myofibroblastic tumors from their malignant mimics.

Inflammatory pseudotumours of the urinary bladder in dogs resembling human myofibroblastic tumours: a report of eight cases and comparative pathology

Eight cases of inflammatory myofibroblastic tumours (IMT) of the urinary bladder in dogs are described, including their clinical, imaging, morphological, and histopathological aspects. Old small breed female dogs were more commonly affected. Haematuria was the main clinical sign, often associated with dysuria and crystalluria. The IMT appeared as single or multiple, polypoid, firm masses, measuring 1-7 cm. Histologically, the masses were well delineated, covered by a benign hyperplastic urothelium and diffusely infiltrated by a mixed inflammatory component. The cells were spindle-shaped, adopting a fascicular, pallisading or whirling organisation and were vimentin and variably desmin and actin positive. The nuclei were globular, containing open chromatin and prominent nucleoli. Mild to moderate pleomorphism and little mitotic activity were present. These morphological features are compatible with human myofibroblastic inflammatory tumours.

Miscellaneous Pseudotumors and Mesenchymal Tumors of the Female Genital Tract

Benign and malignant soft tissue tumors and pseudotumors can rarely arise anywhere in the female genital tract. Their pathologic features as well as behavior typically overlap with those described in tumors involving typical locations. However, due to their rarity, not infrequently these tumors represent a diagnostic challenge. Their diagnosis should be based on careful gross examination, thorough sampling, and morphologic evaluation, applying a selected immunohistochemical panel and molecular studies. Accurate classification of these tumors is important because their clinical behavior, prognosis, and therapy differ markedly. This article outlines several mesenchymal lesions reported in the female genital tract, encompassing recent histologic, immunohistochemical, and molecular findings, with special emphasis on problems in the differential diagnosis.

Uterine sarcomas in Norway. A histopathological and prognostic survey of a total population from 1970 to 2000 including 419 patients

AIMS

To determine the frequency and survival of the various types of uterine sarcoma in the total population of Norway and evaluate histopathological prognostic factors in order to identify risk groups.

METHODS AND RESULTS

Histopathological review of all uterine sarcoma cases reported to the Norwegian Cancer Registry during 1970-2000 was undertaken. Survival dates were provided by The Cancer Registry. Kaplan-Meier survival curves were generated. The log rank test was used for univariate analysis and a Cox proportional hazards regression model for multivariate evaluation of survival. Stage of disease was the most important prognostic factor for all tumour types. Tumour size and the mitotic index (MI) were significant prognostic factors (P < 0.0001) in leiomyosarcomas confined to the uterus and allowed for separation into three risk groups with marked differences in prognosis. The prognosis of endometrial stromal sarcomas confined to the uterus was related to MI (P < 0.0001) and tumour cell necrosis (P < 0.004). Combining these parameters allowed for separation into three risk groups with marked difference in prognosis. In adenosarcomas, tumour cell necrosis was the only significant prognostic factor.

CONCLUSIONS

There are marked differences in survival between uterine sarcoma types. Leiomyosarcomas and endometrial stromal sarcomas can be divided into different groups.

Inflammatory myofibroblastic tumor and low-grade myofibroblastic sarcoma: a comparative study of clinicopathologic features and further observations on the immunohistochemical profile of myofibroblasts

Inflammatory myofibroblastic tumor (IMT) and low-grade myofibroblastic sarcoma (LGMS) are intermediate- or low-grade malignant myofibroblastic neoplasms. In this study, the clinicopathologic profiles of 24 IMTs and 10 LGMS were compared with a focus on the immunohistochemical profiles of the neoplastic myofibroblasts. The primary antibodies used in this study were specific for the ultrastructural subcellular components: (1) *-smooth muscle actin (*-SMA), muscle-specific actin (MSA), calponin, and h-caldesmon for myofilaments; (2) fibronectin for fibronexus; (3) laminin for basal lamina; (4) desmin and cytokeratin for intermediate filaments. Anaplastic lymphoma kinase (ALK) alterations were examined by immunohistochemical means, with selective fluorescence in situ hybridization analysis. Histologically, IMT had inhomogeneous microscopic features with multi-component and multi-patterned architecture, whereas LGMS tended to be more uniform in appearance with a higher cellularity, more prominent nuclear hyperchromasia, and a more widely infiltrative growth pattern than IMT. Immunohistochemically, firstly, more than 90% of the cases of both IMT and LGMS expressed calponin, *-SMA, MSA, and fibronectin, almost all with a high expression level, and no cases were positive for h-caldesmon. Secondly, 33.3% (7/21) of IMTs and 40% (4/10) of LGMS were positive for desmin with a low expression level. The positive percentage for laminin was 81.8% (18/22) in IMT, but was 42.9% (3/7) in LGMS with a low expression level. Thirdly, 13.6% (3/22) of IMTs were positive for cytokeratin, but no expression was found in LGMS. ALK staining was found in 40.9% (9/22) of IMTs, and the presence of ALK gene rearrangements was confirmed by fluorescence in situ hybridization in 5 of 6 IMTs examined. However, neither ALK gene rearrangements nor ALK protein labeling was detected in LGMS (0/9). In summary, IMT and LGMS are both composed of cells displaying well-developed myofibroblastic differentiation, which frequently and extensively express actin-associated proteins (*-SMA, MSA, and calponin) and fibronectin, consistent with the ultrastructure markers (myofilaments and fibronectin fibrils). Laminin expression does not exclude a diagnosis of myofibroblastic neoplasms. ALK and cytokeratin, when positive, can be helpful in differentiating IMT from LGMS. LGMS is not a member of the family of ALK-positive tumors.