Beyond Smooth Muscle-Other Mesenchymal Neoplasms of the Uterus.

Mesenchymal tumors of the uterus comprise a heterogeneous group of neoplasms of varied biologic potential. In addition to being host to several anatomically unique entities, the uterus may contain mesenchymal neoplasms typically found elsewhere in the body. Although smooth muscle neoplasms are common, other mesenchymal neoplasms in this location are relatively rare. Many of these neoplasms exhibit morphologic overlap. In addition to a careful histomorphologic review, definitive classification frequently depends on the judicious application of ancillary immunohistochemical and molecular testing. The intent of this review is to offer a basic approach to the classification of primary uterine mesenchymal neoplasms.

Criteria for Risk Stratification of Vulvar and Vaginal Smooth Muscle Tumors: An Evaluation of 71 Cases Comparing Proposed Classification Systems.

Accurate risk stratification of smooth muscle tumors (SMTs) is essential for appropriate patient management. Yet, the rarity of SMTs of the vagina and vulva makes development of a prognostically meaningful classification system challenging. While 2 classification methods for vulvar SMTs and 1 for vaginal SMTs have been proposed, it is our experience that many pathologists tend to apply criteria for uterine SMTs when evaluating vulvovaginal tumors. We retrospectively reviewed a large cohort of vulvovaginal SMTs with clinical follow-up and evaluated which method most accurately classified tumors according to patient outcome. A total of 71 tumors, 53 vaginal (75%) and 18 vulvar (25%), from 71 patients were identified. All tumors were centrally examined for degree of cytologic atypia, morphology (spindled, epithelioid, myxoid), mitotic index per 10 high power fields, atypical mitotic figures, tumor cell necrosis, ischemic necrosis, tumor interface (circumscribed or infiltrative) and margin status. Clinical features were recorded for each patient. Follow-up was available for 63 patients (89%), and ranged from 1 to 234 months (median: 64 mo). While site-specific and uterine criteria showed equally excellent sensitivity in classifying smooth muscle neoplasms as leiomyosarcoma according to patient outcome, uterine criteria showed improved specificity relatively to site-specific methods in classifying tumors as nonsarcoma according to patient outcome. We recommend that uterine SMT criteria and nomenclature be adopted for evaluation and classification of vulvovaginal SMTs.

[Uterine smooth muscle tumors--determination of clinical behavior and classification].

The establishment of the clinical behavior of uterine smooth muscle tumors /USMT/ is an essential stage of modern diagnostics. There are significant differences in the criteria determining the malignant potential of smooth muscle gynecological tumors. Generally USMT generating diagnostic problems are classified into: clinically benign tumors; clinically malignant tumors with benign morphological features; smooth muscle tumors of uncertain malignant potential (SMTUMP) and lesions whose smooth muscle differentiation is not obvious. The knowledge in this area is essential for an adequate therapeutic approach.

From PTEN loss of expression to RICTOR role in smooth muscle differentiation: complex involvement of the mTOR pathway in leiomyosarcomas and pleomorphic sarcomas.

Over the past decade, comprehensive genomic studies demonstrated that leiomyosarcomas and most of the tumors previously labeled as 'malignant fibrous histiocytomas' share complex karyotypes and genomic profiles, and can be referred to as 'sarcomas with complex genomics'. We recently reported a series of 160 sarcomas with complex genomics such as leiomyosarcomas, myxofibrosarcomas, pleomorphic liposarcomas/rhabdomyosarcomas and undifferentiated pleomorphic sarcomas. These tumors present with a frequent loss of chromosome 10 region encompassing the tumor suppressor gene PTEN. In the present study, we assessed PTEN genomic level and protein expression in this large series of sarcomas with complex genomics, as well as activation of downstream pathways. PTEN partial genomic loss was observed in only 46% of tumors, especially in well-differentiated leiomyosarcomas, whereas up to 68% of these tumors demonstrate a loss of protein expression on western blot analysis. Specific discrepancies in PTEN immunohistochemical results suggested bias in this latter technique. PTEN mutations were rare, with only 4 point mutations in the 65 samples studied. Subsequent activation of AKT and mTOR pathways was only observed in 2 out of 3 of PTEN-deleted tumors. On the other hand, RICTOR, a major component of the mTOR complex 2, was significantly overexpressed in well-differentiated leiomyosarcomas. These results, confirmed on tissue micro-array immunohistochemical analysis of 459 sarcomas, could suggest a link between RICTOR overexpression and leiomyosarcomas oncogenesis. As therapeutics directed against the mTOR pathway are assessed in sarcomas, RICTOR overexpression in sarcomas and its links to therapeutic response need to be assessed.

Use of myocardin in the classification of mesenchymal tumors of the uterus.

It can sometimes be difficult to distinguish between the 2 main types of uterine mesenchymal neoplasms; uterine smooth muscle tumors (SMTs) and endometrial stromal sarcomas (ESSs), particularly when the ESSs show smooth muscle differentiation or the SMTs are highly cellular. The aim of this study was to investigate myocardin expression in normal uterus myometrium, in SMTs, and in ESSs and to determine whether myocardin can be used as a useful diagnostic tool in the classification of problematic uterine mesenchymal tumors. Immunohistochemical staining was performed in each group. Besides myocardin, all cases were also stained for other smooth muscle markers (h-caldesmon, desmin, smooth muscle actin) and for CD10. All tested markers were analyzed in 21 conventional leiomyomas (LMs), 21 highly cellular leiomyomas (HCLs), 12 leiomyosarcomas (LMSs), 3 endometrial stromal nodules (ESNs), 11 ESSs, and 15 normal uterus myometrium. Myocardin was expressed in all normal uterine myometrium and in SMTs (even in the regions with epithelioid features) moderately or strongly, at least topically, whereas in endometrium, in ESNs and in ESSs, except in the regions of smooth muscle differentiation, it was negative. All ESNs, 11 of 11 ESSs and 14 of 15 endometrium were negative for h-caldesmon, but all SMTs and normal uterine myometrium were positive for h-caldesmon except for 2 LMSs, 2 HCLs, and for the regions with epithelioid features in 2 LMs. Desmin was stained in all normal uterine myometrium and in SMTs (except those of the regions with epithelioid features), but it was negative in 1 HCL and 1 LMS. One of 3 ESNs and 2 of 11 ESSs were expressed in desmin. Smooth muscle actin was negative in all ESNs, 2 LMSs, and 2 HCLs, and positive in all myometriums, LMs (except for the regions with epithelioid features), 1 ESSs, and 1 proliferative phase endometrium. Eight of 11 ESSs and all ESNs were positive for CD10, as was 1 HCL, and 2 LMSs. All uterine myometrium, 3 ESSs, and 3 endometriums were negative for CD10. Our study indicates that the myocardin is expressed in normal and neoplastic uterine smooth muscle cells sensitively and that the evaluation of myocardin expression is useful in distinguishing SMTs from ESSs.

Diagnostic criteria for uterine smooth muscle tumors: leiomyoma variants associated with malignant behavior.

OBJECTIVE: To determine the prognostic accuracy of current diagnostic criteria for uterine smooth muscle tumors. STUDY DESIGN: Cases of uterine leiomyosarcoma (LMS) treated from 1976 to 1999 were analyzed retrospectively. Uterine LMS specimens were reevaluated using current criteria by a pathologist specializing in gynecologic diseases. Kaplan-Meier survival curves were evaluated. RESULTS: Specimens were available from 67 patients diagnosed with uterine LMS. On rereview, only 47 specimens were thought to represent uterine LMS. The 20 other patients were deemed to have leiomyomas or leiomyoma variants, including 13 cellular leiomyomas, 5 atypical leiomyomas and 2 leiomyomas. Median survival for patients with uterine LMS was 2.1 years. (Ninety-seven percent of disease-specific deaths occurred within 6 years after the diagnosis.) With leiomyoma variants, median survival was > 25 years. Among these 18 women were 3 disease-specific deaths (all > 6 years after diagnosis). CONCLUSION: Diagnostic criteria for uterine smooth muscle tumors require continued refinement. A small but significant number of patients diagnosed with leiomyoma variants will die of the disease. In contrast to the aggressive behavior of uterine LMS, disease-specific deaths attributed to leiomyoma variants occurred later. With this potential for delayed recurrence, these patients warrant close clinical surveillance.

Use of histone deacetylase 8 (HDAC8), a new marker of smooth muscle differentiation, in the classification of mesenchymal tumors of the uterus.

UNLABELLED: Uterine smooth muscle tumors (SMTs) are usually recognized on the basis of their routine morphologic features; however, their distinction from endometrial stromal tumors (ESTs), the second most common mesenchymal tumor of the uterus, is sometimes problematic. Histone deacetylases (HDACs) were originally identified as nuclear enzymes regulating histone acetylation. We have recently shown that in normal human tissues, HDAC8 is exclusively expressed in the cytoplasm of cells showing smooth muscle differentiation. In this study, we examined HDAC8 expression in SMTs and ESTs of the uterus to determine whether HDAC8 may be a useful diagnostic tool in the classification of problematic uterine mesenchymal tumors. HDAC8 immunohistochemical staining was performed in 15 leiomyomas (LMs), 9 highly cellular leiomyomas (HCLs), 8 epithelioid SMTs, 13 leiomyosarcomas (LMSs), and 17 ESTs, including 3 with sex-cord differentiation and 5 with smooth muscle differentiation. All tumors were also stained for other smooth muscle markers (desmin, h-caldesmon, smooth muscle actin [SMA], smooth muscle myosin heavy chain) and for CD10. All LMs had moderate to strong expression of all smooth muscle markers. HDAC8 was detected in 8 of 9 HCLs and in all epithelioid SMTs (8 of 8); however, it was weak in 4 epithelioid SMTs. In contrast, desmin, h-caldesmon and smooth muscle myosin were positive in only 2 of 8, 1 of 8 and 4 of 8 epithelioid SMTs, respectively. All smooth muscle markers had similar frequency of staining in LMSs; however, HDAC8 showed overall moderate intensity compared with other smooth muscle markers, which showed stronger staining. HDAC8, h-caldesmon, and smooth muscle myosin did not stain conventional areas of ESTs or ESTs with sex-cord differentiation, whereas SMA and desmin were positive in those areas in 4 of 12 and 3 of 12 ESTs, respectively. Areas of smooth muscle differentiation in ESTs were positive for HDAC8 in all cases, but they were less constantly positive for the other smooth muscle markers. CD10 was expressed in most ESTs (14 of 17), but it was also positive in 15 of 45 SMTs. IN CONCLUSION: 1) HDAC8 seems to be a specific marker of SM differentiation because conventional ESTs and ESTs with sex-cord differentiation are negative for HDAC8, whereas areas of smooth muscle differentiation in these tumors are consistently positive; 2) HDAC8 gives similar results to those obtained with desmin, h-caldesmon, and smooth muscle myosin in both LMs and LMSs, although the staining for HDAC8 in LMSs tends to be less intense; 3) HDAC8 may be a more sensitive marker than desmin and h-caldesmon in epithelioid SMTs. Thus, HDAC8 detection may be useful in helping the differential diagnosis of uterine mesenchymal tumors.

Perivascular epithelioid cell tumor ('PEComa') of the uterus: a subset of HMB-45-positive epithelioid mesenchymal neoplasms with an uncertain relationship to pure smooth muscle tumors.

The family of lesions thought to be composed at least in part of perivascular epithelioid cells, characterized as HMB-45-positive epithelioid cells with clear to eosinophilic granular cytoplasm and a propensity for a perivascular distribution, includes some forms of angiomyolipoma and lymphangioleiomyomatosis, as well as clear cell "sugar" tumor (CC-SUGAR). When composed predominantly or exclusively of epithelioid cells, it has been suggested that these lesions be classified as "perivascular epithelioid cell tumors" (PEComa). Four cases of uterine PEComa have been described in the literature, three of which exhibited aggressive behavior. We report the clinical, histologic, and immunohistochemical features of eight more examples of uterine PEComa. Patients ranged in age from 40 to 75 years (mean 54 years). Most patients presented because of abnormal uterine bleeding, and grossly a mass was present in the uterine corpus. Morphologically, the tumors could be divided into two groups (A and B). Group A tumors demonstrated a tongue-like growth pattern similar to that seen in low-grade endometrial stromal sarcoma and were composed of cells that tended to have abundant clear to eosinophilic pale granular cytoplasm, diffuse HMB-45 expression, and focal muscle marker expression. Group B tumors were composed of epithelioid cells with less prominent clear cell features, smaller numbers of which were HMB-45-positive. They also featured extensive muscle marker expression and a lesser degree of the endometrial stromal sarcoma growth pattern seen in group A tumors. Two of the four patients with group B tumors had pelvic lymph nodes involved by lymphangioleiomyomatosis, and one of these patients had the tuberous sclerosis complex. Seven of the eight patients with PEComas were treated by hysterectomy. All eight patients are alive and well, although follow-up of >2 years was available only for two patients. Uterine epithelioid smooth muscle tumors and low-grade endometrial stromal sarcomas were compared with the PEComas. Group A PEComas, group B PEComas, and epithelioid smooth muscle tumors were all parts of a continuous histologic spectrum, with group A PEComa at one end of the spectrum and epithelioid smooth muscle tumors at the other, while group B tumors shared features of both. PEComa was histologically and immunohistochemically distinct from endometrial stromal sarcoma. Our data and a review of the literature indicate that PEComa is a subset of HMB-45-positive epithelioid mesenchymal tumors of the uterus with an uncertain relationship to pure smooth muscle tumors. Although none of the patients in this study experienced recurrence during a short follow-up period, some reported in the literature have had recurrences; consequently, we think uterine PEComa should be considered a tumor of uncertain malignant potential until long-term outcome data for a larger number of patients become available.

Do leiomyomas of deep soft tissue exist? An analysis of highly differentiated smooth muscle tumors of deep soft tissue supporting two distinct subtypes.

There is a prevailing view that leiomyomas of deep soft tissue are rare or nonexistent, but there are limited data on this subject in the form of large clinical studies with long follow-up information. We reviewed 36 consultation cases that had been diagnosed as leiomyoma or probable leiomyoma based on absence of nuclear atypia, necrosis, and no/minimal mitotic activity. Follow-up information was obtained to determine whether these stringent histologic criteria could identify a biologically benign group of smooth muscle tumors of deep soft tissue. The tumors occurred in two distinct locations. The first (n = 13) occurred in deep somatic soft tissue of the lower extremity (7), upper extremity (2), trunk (2), axilla (1), and back (1) and affected the sexes equally (7 male, 6 female). Composed of a circumscribed mass of mature smooth muscle cells, they were frequently calcified with a mean mitotic activity of <1 mitosis/50 high power fields (HPF) (range 1-4 mitoses/50 HPF). Estrogen receptor and progesterone receptor proteins were negative in the three cases tested. No tumors recurred or metastasized (mean follow-up 58.7 months, range 5-97 months). The second group (n = 23) occurred within the retroperitoneum (20) or abdominal cavity (3) of women (1 male, 22 female). Resembling uterine leiomyomas, they were always distinct from the uterus, occasionally multiple (n = 4), and sometimes occurred up to years after hysterectomy (n = 3). Four cases occurred with synchronous uterine leiomyomas. In the six cases tested, five of six were positive for the estrogen receptor protein and all were positive for progesterone receptor protein. Mean mitotic activity was 1 mitosis/50 HPF (range <1-10 mitoses/50 HPF). None developed metastasis within the follow-up period (mean 42.5 months, range 6-120 months); one tumor with a positive margin recurred at 10 months. We conclude that clinically benign smooth muscle tumors of deep soft tissue are rare but can be identified using stringent histologic criteria. They comprise two distinct subtypes: leiomyomas of somatic soft tissue and retroperitoneal-abdominal leiomyomas. The latter probably arise from hormonally sensitive smooth muscle. Although similar to uterine leiomyomas, they are located at sites removed from the uterus and are likely independent soft tissue primaries rather than parasitic leiomyomas of the uterus. We suggest that these two groups of smooth muscle tumors be diagnostically approached in a site-specific fashion.

Methodological aspects of using decision trees to characterise leiomyomatous tumors.

The aim of the present work is to present the potential uses of a classification technique labeled the "decision tree" for tumor characterisation when faced with a large number of features. The decision tree technique enables multifeature logical classification rules to be produced by determining discriminatory values for each feature selected. In this report, we propose a methodology that used decision trees to compare and evaluate the information contributed by different types of features for tumor characterisation. This methodology is able to produce a set of hypotheses related to a diagnosis and or prognosis problem. For example, hypotheses can be producted (on the basis of a set of descriptive features) to explain why tumor cases belong to a given histopathological group. To illustrate our purpose, this methodology was applied to the difficult problem of leiomyomatous tumour diagnosis. The aim was to illustrate what kind of diagnostic information can be extracted from a sample data set including 23 smooth muscle tumors (14 benign leiomyomas and 9 malignant leiomyosarcomas) described by a large set of computer-assisted, microscope-generated features. Three groups of features were used relating to: (1) ploidy level determination (10 features), (2) quantitative chromatin pattern description (15 features), and (3) immunohistochemically related antigen specificities (6 features). All these features were quantified by digital cell image analysis. The results suggest that an objective distinction between leiomyomas and leiomyosarcomas can be established by means of simple logical rules depending on only a few features among which the immunohistochemically revealed antigen expression of desmin plays a preponderant part. One of the combinations of features proposed by the methodology is interesting for pathologists, because it includes two features describing the appearance of a nucleus in terms of chromatin distribution homogeneity and density, two features widely used by pathologists in tumor-grading systems.

Metástasis pulmonares tardías como forma de presentación de un leiomiosarcoma uterino / Late pulmonary metastases as presentation way of a uterine leiomyosarcoma

Una mujer de 56 años posterior a una histerectomía por leimiomatosis atípica, debuta con metástasis pulmonares de un leimiosarcoma, sin evidencias de otro foco primario que el uterino. Realizamos una revisión y discusión del tema, motivados por la rara forma de presentación y evolución de la lesión maligna

A comparative immunohistochemical study of uterine smooth muscle neoplasms with emphasis on the epithelioid variant.

We evaluated the immunophenotypes of 22 spindled and 36 epithelioid uterine smooth muscle neoplasms (SMNs) and 16 extrauterine nongastrointestinal spindled smooth-muscle neoplasms for various markers. The epithelioid neoplasms were subdivided into two histological groups designated true and intermediate, the former showing typical epithelioid features and the latter showing epithelioid features that could be explained by cross-sectioning of blunt spindled cells. Desmin, muscle-specific actin, and smooth muscle actin were equally sensitive in detecting muscle differentiation in all these neoplasms. The true epithelioid variants were more frequently keratin positive but less frequently positive for vimentin, CD34 or the muscle markers, compared with their spindled counterparts. The intermediate epithelioid variants more closely resembled the spindled neoplasms in their immunostaining for muscle markers, vimentin, and CD34 but like the true epithelioid variants were relatively frequently positive for keratin. CD34 was positive in 36% of the spindled and 6% of the true epithelioid uterine SMNs, in most cases faintly. Antikeratin AE1 was positive more frequently than CAM5.2, with 18% of the spindled and 35% of the true epithelioid neoplasms being AE1 positive. The immunophenotype of uterine SMNs, including the epithelioid variant, permits their distinction from carcinomas based on their frequent reactivity for muscle markers in spite of their high rate of keratin positivity. They show sufficient overlap in immunoreactivity with endometrial stromal sarcomas to preclude definitive differentiation from them on immunohistochemical features alone.