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

Unlocking immunotherapy targets: programmed death 1 and its ligand and their correlation with tumour grade in feline injection site sarcoma

In this study, the immunohistochemical expression of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1), which could facilitate a novel approach to immunotherapy for feline injection site sarcomas (FISSs), was investigated. Treatment strategies based on the suppression of this pathway are possible for tumours expressing PD-1/PD-L1. In this context, FISSs were histologically classified, the grade of sarcoma and the intensity of lymphocyte infiltration determined and PD-1 and PD-L1 expression evaluated in tumours of different grade. Tumours were immunolabelled for vimentin, S100, smooth muscle actin and sarcomeric actin. Fibrosarcoma was diagnosed in eight cases, undifferentiated sarcoma in one case, liposarcoma in one case and rhabdomyosarcoma in one case. PD-1 expression was found mainly in lymphoid infiltrations and macrophage-like cells, while PD-L1 was found primarily in tumour cells and infiltrated macrophage-like cells. By Pearson correlation analysis, tumour differentiation was found to have a moderate correlation with PD-1 (P <0.05) and a high correlation with PD-L1 (P <0.01). Tumour grade had a low correlation with PD-1 and a moderate correlation with PD-L1 (P >0.05). A moderate correlation was also detected between PD-1 and PD-L1 (P <0.05). It was concluded that the increased expression of PD-1 and PD-L1 may be associated with poor tumour differentiation and, therefore, poor prognosis in FISS.

Histopathological Evaluation and Molecular Diagnostic Tests for Peritoneal Metastases with Unknown Primary Site-a Review

Cancer of unknown primary (CUP) is a well-studied entity with guidelines available for the management of patients with CUP. The peritoneum represents one of the metastatic sites in CUP, and peritoneal metastases (PM) could present as CUP. PM of unknown origin remains a poorly studied clinical entity. There is only one series of 15 cases, one population-based study, and few other case reports on this subject. Studies on CUP, in general, cover some common tumour histological types like adenocarcinomas and squamous carcinomas. Some of these tumours may have a good prognosis though majority have high-grade disease with a poor long-term outcome. Some of the histological tumour types commonly seen in the clinical scenario of PM like mucinous carcinoma have not been studied. In this review, we divide PM into five histological types-adenocarcinomas, serous carcinomas, mucinous carcinomas, sarcomas and other rare varieties. We provide algorithms to identify the primary tumour site using immunohistochemistry when imaging, and endoscopy fails to establish the primary tumour site. The role of molecular diagnostic tests for PM or unknown origin is also discussed. Current literature on site-specific systemic therapy based on gene expression profiling does not show a clear benefit of this approach over empirical systemic therapies.

Solitary Fibrous Tumors of the Female Genital Tract: A Study of 27 Cases Emphasizing Nonvulvar Locations, Variant Histology, and Prognostic Factors

We report 27 solitary fibrous tumors of the female genital tract emphasizing nonvulvar locations, variant histology, and prognostic factors. The patients ranged from 25 to 78 years (most were over 40), and tumors occurred in the vulva (7), vagina (2), cervix (2), corpus (6), fallopian tube/paratubal soft tissue (5), and ovary (5). They ranged from 1.5 to 39 (mean=10.5) cm and were typically solid, but 4 were predominantly cystic. All had a haphazard arrangement of spindled to ovoid cells, with most demonstrating alternating cellular and hypocellular areas and prominent vessels, but 13 lacked hypocellular areas, and 7 had focal diffuse growth with inconspicuous vasculature. Other patterns included corded (8), fascicular (5), trabecular (1), and nested (1). Microcysts (6), myxoid background (8), hyalinization (8), lipomatous differentiation (2), and multinucleated cells (6) were also present, and 10 tumors had necrosis. Vasculature included thin-walled branching "staghorn" (27), thick-walled (7), and hyalinized vessels (5) or dilated anastomosing vascular channels (3). Nuclear atypia ranged from mild (19), moderate (7), to severe (1), and mitoses from 0 to 24/10 HPF (mean=4). STAT6 was positive in all 25 tumors tested. One tumor showed dedifferentiation; the remainder were classified as benign (19) or malignant (7) based on mitotic rate (univariate stratification model) and as low risk (14), intermediate risk (8), or high risk (4) based on the Demicco multivariate risk stratification score. Follow-up (median=23 mo) was available for 16 patients. Six tumors recurred (2 intermediate risk, 3 high risk, and the dedifferentiated tumor), 5 in the abdomen; the dedifferentiated tumor metastasized to the lung. Multivariate risk stratification was superior to univariate classification, as 5 "benign" tumors were reclassified as intermediate risk using the multivariate model; of these, 2 recurred, and 1 patient died of disease. Upper female genital tract tumors occurred in older patients, were larger, and more frequently classified as high risk compared with those of the lower tract. A trend toward increased cellularity was also seen in the upper tract tumors. Only size (P=0.04), necrosis (P=0.04), and Demicco score (P=0.01) independently correlated with recurrence. Female genital tract solitary fibrous tumors demonstrate a wide range of variant morphologies and occur in diverse sites in addition to the vulva. Tumors were often misdiagnosed as other neoplasms; thus, awareness of solitary fibrous tumors occurring at these sites is crucial in prompting staining for STAT6 to establish this diagnosis. The Demicco risk stratification system effectively predicts behavior.

Uterine leiomyosarcoma: A review of the literature and update on management options

Uterine leiomyosarcoma is the most common type of uterine sarcoma. It is an extremely aggressive malignancy associated with a poor overall prognosis. Women affected may vary in age, but are most often diagnosed in their perimenopausal years. Presenting symptoms may be vague and mimic other benign uterine conditions. Preoperative diagnosis of leiomyosarcoma is difficult and often only made at time of surgical resection. These rare mesenchymal tumors are characterized by cytologic atypia, a high mitotic index, and tumor necrosis on histologic inspection. Management of early stage disease entails hysterectomy and complete surgical resection of gross tumor, though routine oophorectomy or lymph node dissection do not appear to confer much clinical benefit. Adjuvant therapy for early stage disease remains controversial as multiple clinical trials have failed to demonstrate benefit on overall survival. Recently, progress has been made in regards to therapy for advanced and recurrent disease. Novel chemotherapeutics, targeted therapies such as olaratumab and pazopanib, and new immunotherapies such as nivolumab and pembrolizumab have demonstrated promise in these previously difficult drug-resistant patients. In this article, we provide a detailed review of uterine leiomyosarcoma including epidemiology, clinical presentation, diagnosis, and pathologic characteristics. We then go on detail management strategies, including options for adjuvant therapy, and highlight new and developing regimens in the field.

[Dermatofibrosarcoma protuberans: report of 38 cases]

Le dermatofibrosarcome protubérans de Darier et Ferrand est une tumeur cutanée rare. Le but de cette étude est de décrire les aspects épidémiologiques, cliniques, histologiques, thérapeutiques et évolutifs avec comparaison aux données de la littérature. Il s'agissait d'une étude rétrospective sur 10 ans à propos de 38 cas de dermatofibrosarcome de Darier et Ferrand pris en charge à l'Institut National d'Oncologie. Les données épidémiologiques, diagnostiques, thérapeutiques et évolutives ont été recueillies à partir des dossiers cliniques des patients et rapportées sur une fiche préétablie. L’âge médian des patients était de 41,5 ans. Tous les patients avaient une preuve histologique de dermatofibrosarcome. Seulement 30 patients ont été traités à l'Institut National d'Oncologie. L'exérèse chirurgicale de la tumeur était large, avec des marges de sécurité de 6-10 cm chez 6 patients (20%), 5 cm chez 16 patients (53%), 2-3 cm chez 4 patients (13%). En profondeur, l'exérèse emportait une barrière anatomique saine. 5 malades ont bénéficié d'une radiothérapie externe avec une dose médiane de 59,5 Gy. Le recul médian était de 64,4 mois (28- 138 mois). Le dermatofibrosarcome protubérans de Darier et Ferrand est une tumeur se distinguant par son évolution lente, son agressivité locale, son haut pouvoir de récidive et la rareté des métastases. Le traitement consiste en une exérèse large et profonde. Le pronostic dépend essentiellement de la qualité de l'exérèse initiale chirurgicale. La série étudiée présente des similitudes épidémiologiques, cliniques, et thérapeutiques avec les données de la littérature.

Smooth Muscle Tumors of the Female Genital Tract

Smooth muscle tumors are the most common among mesenchymal tumors in the female genital tract. The vast majority of these neoplasms are clinically benign and easy to diagnose. In contrast, leiomyosarcomas are highly aggressive tumors that may pose considerable diagnostic problems when they display unusual (myxoid or epithelioid) morphology, ambiguous histologic features for malignancy, or an unusual anatomic distribution. Diagnostic criteria for these problematic tumors vary depending on the site and type of histologic differentiation, and are based on a combination of 3 major criteria: (1) moderate to severe cytologic atypia; (2) increased mitotic index; and (3) tumor cell necrosis. Certain benign smooth muscle proliferations may show worrisome histologic features or unusual growth patterns, causing concern for leiomyosarcoma. Furthermore, other tumors, including perivascular epithelioid tumors, may mimic leiomyosarcoma. Careful attention to the clinical and anatomic setting, cytologic and architectural features, and immunohistochemical characteristics are helpful in distinguishing these entities. This article discusses conventional smooth muscle tumors as well as unusual subtypes, with emphasis on the diagnostic criteria and problems in differential diagnosis that arise at each site within the female genital tract.

Application of immunohistochemistry to gynecologic pathology

CONTEXT

A large variety of tumors and lesions arise in the female genital tract. Although the majority of these can be correctly recognized on routine hematoxylin-eosin-stained slides, occasional cases present a diagnostic challenge. Immunohistochemical stains are extremely useful in resolving many of these problematic cases. As the knowledge in this area is constantly expanding, it is useful to have this updated information in a review form for easy access.

OBJECTIVE

To present our current knowledge of immunohistochemistry of the lesions of the female genital tract in a readily accessible form.

DATA SOURCES

The review is based on previously published articles on this topic.

CONCLUSIONS

Immunohistochemical stains help in reaching a conclusive diagnosis in a variety of problematic lesions seen in gynecologic pathology. As in any other system, immunohistochemical findings need to be interpreted in light of the clinical history and morphologic findings.

Uterine PEComa: appraisal of a controversial and increasingly reported mesenchymal neoplasm

In recent years, a group of tumors that have been designated "perivascular epithelioid cell tumors" (PEComa) have been reported with increasing frequency from a wide variety of anatomic locations. The uterus and retroperitoneum appear to be the most frequent sites of origin for these lesions. PEComas belong to an identically named family of tumors comprised of conventional angiomyolipomas, clear cell sugar tumors, lymphangiomyomatosis and clear cell myomelanocytic tumor of the falciform ligament/ligament teres, and are also known as PEComa-NOS. This article is a primer for clinicians on the most salient clinicopathologic features of uterine PEComas, as most of the debate and discussion have taken place in the pathologic literature. The author appraises in detail the current state of knowledge on PEComas of the uterus based on a review of published data on the 44 previously reported cases, and comments on areas of controversy. The latter are centered predominantly on the significant morphologic and immunophenotypic overlap that exists between uterine PEComa and some smooth muscle tumors of the uterus. The clinicopathologic features of cases reported as epithelioid smooth muscle tumors and cases reported as uterine PEComas are compared and contrasted, and a practical approach to their reporting is proposed.

Corpora amylacea in a leiomyoma of soft tissue

A case of myxoid leiomyoma of deep soft tissue is described. The patient was a 42-year-old woman who presented with menorrhagia, and an ischiorectal mass was identified. A total hysterectomy was performed, and the mass was removed. On gross examination, the mass was 6cm x 5cm x 4cm and had a mucoid cut surface. Histologic examination revealed a myxoid leiomyoma with abundant intracellular corpora amylacea (CA). An infarcted leiomyoma was present in the hysterectomy specimen. The patient remains well, with no evidence of recurrence 3 years after surgery. Leiomyomas of deep soft tissue are rare, and, to our knowledge, none have been described containing CA.

Mixed tumors of the vagina: an immunohistochemical study of 13 cases with emphasis on the cell of origin and potential aid in differential diagnosis

Mixed tumors of the vagina (MTsV) are rare benign neoplasms characterized by an admixture of well-differentiated epithelial cells and stromal-type cells in various proportions. In contrast to mixed tumors in other anatomic sites, the histogenesis of the vaginal tumors is unclear. We studied the immunohistochemical profile of 13 examples to explore their histogenesis and determine whether their immunohistochemical profile might be useful in the differential diagnosis. The panel of antibodies used and the number of cases studied were: AE1/3 (12), cytokeratin 7 (CK7) (13), cytokeratin 20 (CK20) (13), epithelial membrane antigen (EMA) (13), muscle actin (MA) (12), desmin (11), h-Caldesmon (13), CD10 (13), CD34 (11), CD99 (8), and S-100 (7). Eight out of 12 tumors were positive for AE1/3, 7/13 for CK7, 2/13 for CK20, and 6/13 for EMA. MA was positive in 11/12 mixed tumors, desmin in 10/11 tumors and h-Caldesmon in 5/13. All tumors were extensively positive for CD10; CD34 was positive in 7/11; and none out of eight tumors showed membranous CD99 staining. Focal S-100 immunoreactivity was seen in 1/7 tumors. These results show that MTsV coexpress epithelial and mesenchymal markers. The expression of muscle actin (usually extensive), and focal desmin and h-Caldesmon positivity suggests the presence of a smooth muscle or myoepithelial component; however, the S-100 negativity and diffuse CD10 expression argue against it. Positivity for muscle markers does not help distinguish MTsV from smooth muscle or skeletal muscle tumors. The frequent expression of CD10 negates its use in the differential diagnosis with endometrial stromal tumors, and the CD10 and CD34 expression suggests that mixed tumors may arise from a primitive pluripotential cell. MTsV are positive for h-Caldesmon and CD10, two markers that have been used in gynecologic pathology primarily to aid in establishing the smooth muscle or endometrial stromal phenotype of a neoplasm.

An immunohistochemical analysis of endometrial stromal and smooth muscle tumors of the uterus: a study of 54 cases emphasizing the importance of using a panel because of overlap in immunoreactivity for individual antibodies

The expression of desmin, h-caldesmon, calponin, CD10, CD34, CD99, inhibin, and keratin (AE1/3-Cam 5.2) was studied in 10 conventional leiomyomas, 9 highly cellular leiomyomas, 9 epithelioid smooth muscle tumors, 9 leiomyosarcomas, 10 endometrial stromal tumors (4 with smooth muscle metaplasia), and 7 uterine tumors resembling ovarian sex cord tumors (UTROSCTs). c-kit expression was tested in 10 endometrial stromal tumors, 7 UTROSCTs, and 9 leiomyosarcomas. Desmin was positive in almost all smooth muscle tumors except those of epithelioid type, which were positive in only about half of the cases. It also stained areas of smooth muscle differentiation in endometrial stromal tumors and five of seven UTROSCTs. h-caldesmon was positive in almost all nonepithelioid smooth muscle tumors and in areas of smooth muscle differentiation in endometrial stromal tumors; it was positive in only about half of the epithelioid smooth muscle tumors and negative in all UTROSCTs. Calponin was positive in most tumor types. CD10 was positive in nine of 10 endometrial stromal tumors and five of seven UTROSCTs, although very focally in the latter group. It was also expressed, however, in almost all leiomyosarcomas, almost 50% of highly cellular leiomyomas, and rarely in the other smooth muscle tumors. CD34 was negative in the tested tumors with rare exceptions. CD99 and inhibin were positive in four of seven and one of seven UTROSCTs. Keratin positivity was found in most (five of seven) UTROSCTs and occasionally in smooth muscle tumors (seven of 37). c-kit was negative in all endometrial stromal tumors, UTROSCTs, and leiomyosarcomas. The major conclusions of this study are as follows: 1) Pure endometrial stromal tumors are usually desmin negative. 2) In contrast to some previous studies, CD10 expression was often seen in smooth muscle tumors, including most leiomyosarcomas and almost half of highly cellular leiomyomas. As a result, a panel of CD10, h-caldesmon, and desmin should be used and will distinguish endometrial stromal tumors from highly cellular leiomyomas in most cases. 3) In contrast to a previous study, no significant differences in immunoreactivity were seen between h-caldesmon and desmin in tumors with smooth muscle differentiation. 4) The absence of h-caldesmon in UTROSCTs helps separate them from epithelioid smooth muscle tumors. 5) UTROSCTs may express epithelial, stromal, and smooth muscle markers, suggesting divergent differentiation. 6) Our study shows less frequent inhibin expression in the sex cord-like elements of the UTROSCTs than in other studies. 7) c-kit may help distinguish metastatic endometrial stromal tumors of the uterus (c-kit negative) from gastrointestinal stromal tumors (c-kit positive). 8) CD34, CD99, and keratin have no or minimal role in this area, but keratin positivity in smooth muscle tumors should not lead to their confusion with epithelial tumors.

Epithelioid endometrial and endometrioid stromal tumors: a report of four cases emphasizing their distinction from epithelioid smooth muscle tumors and other oxyphilic uterine and extrauterine tumors

Three endometrial and one extrauterine endometrioid stromal tumors (three sarcomas and one stromal nodule) with a prominent component of epithelioid cells with abundant eosinophilic cytoplasm are described. The patients were 39, 48, 56 and 86 years of age. The endometrial sarcomas were described grossly as an ill-defined tan nodule and "ragged and papillary," respectively, and had the typical infiltrative pattern of low-grade endometrial stromal sarcoma. The stromal nodule was a 13-cm, well circumscribed, yellow, fleshy mass. The extrauterine tumor was probably primary in the sigmoid colon. Oval to polygonal epithelioid cells with abundant eosinophilic cytoplasm accounted for 50% to 90% of the tumor cells. The cytoplasm was granular in one case. None of the tumors contained cells with a rhabdoid appearance. Nuclear and other features did not differ from those of usual endometrial-endometrioid stromal tumors except in one case in which there was greater nuclear pleomorphism. There was strong diffuse cytoplasmic immunoreactivity of all four tumors for vimentin and for CD10 in three of three tumors tested, as well as extensive and moderate reactivity for NK1/C3 and focal weak reactivity for CD68 in two of three tumors tested. Muscle actin positivity was very focal to extensive and weak to strong in all three tumors tested, mainly in the epithelioid areas; alpha-smooth muscle actin was focally to extensively positive in the epithelioid areas of two of three tumors tested; and focal strong desmin positivity (interpreted as indicating smooth muscle metaplasia) was found in the epithelioid areas of one of four tumors. A vaginal recurrence in one case had similar cytologic features to the primary tumor but when examined initially in the absence of adequate history posed diagnostic difficulty, as did evaluation of the uterine tumor in two other cases and the extrauterine tumor in the final case. The differential in these cases is primarily with an epithelioid smooth muscle tumor when they are uterine primaries. The typical infiltration facilitates this distinction in the cases of endometrial stromal sarcomas, but this feature is usually only evident in hysterectomy specimens. In limited samples such as biopsy or curettage specimens, and in some cases of recurrent tumor, awareness that endometrial-endometrioid stromal tumors can have epithelioid cells is crucial in the formulation of the differential diagnosis. Diverse oxyphilic tumors, including deciduoid malignant mesothelioma, can potentially be in the differential diagnosis with extrauterine (endometrioid) stromal sarcomas with epithelioid cells. Immunohistochemical evaluation may potentially provide major aid in diagnosis.

Retroperitoneal leiomyomas: a clinicopathologic and immunohistochemical study of 56 cases with a comparison to retroperitoneal leiomyosarcomas

Most retroperitoneal smooth muscle tumors are believed to be malignant, and leiomyomas are considered very rare. This study was undertaken to determine the clinicopathologic features and long-term follow-up of 56 tumors diagnosed as retroperitoneal leiomyomas (LM) or smooth muscle tumors with an uncertain malignant potential (SMTUMP) in an effort to correlate their behavior and clinicopathologic features. These tumors were compared with a series of 11 cases of retroperitoneal leiomyosarcomas (excluding gastrointestinal stromal tumors). Histologic slides and immunohistochemistry for SMA, desmin, S-100 protein, HMB45, CD34, C-KIT, estrogen (ER) and progesterone (PR) receptor proteins, and MIB-1 were analyzed. All tumors diagnosed as LM and all but one SMTUMP were well-differentiated smooth muscle tumors that lacked atypia and coagulative necrosis. There was <1 mitosis per 50 high power field (HPF) in 38 tumors; no tumor had >3 mitoses/50 HPF. Most tumors had a striking resemblance to uterine smooth muscle tumors with common hyaline change and trabecular patterns. There were 51 females and 5 males ranging in age from 25 to 79 years (mean 45 years, median 43 years). These tumors were typically large, with a mean size of 16.2 cm and weight of 1600 g. Immunohistochemically, all 35 tumors studied were positive for alpha-SMA, 30 of 35 tumors were positive for desmin, and all were negative for CD117, S100 protein, and HMB45 and all but one for CD34. Steroid receptors were commonly present: ER in 20 of 29 cases and PR in 26 of 31 cases in the tumors of female patients. MIB-1 score was <2% in all of 28 cases. Long-term follow-up (mean 140 months) did not reveal metastases, but two patients had local recurrence; however, neither patient with recurrence demonstrated disease progression in follow-up. By contrast, all 11 leiomyosarcomas had at least mild atypia, and all were ER and PR negative. All cases had MIB-1-positive nuclei, but only four had >10% nuclei positive. Four patients died of disease, four were alive with recurrence, and three had no evidence of disease. A group of benign leiomyomas can be identified among retroperitoneal smooth muscle tumors. Most of these tumors resemble uterine leiomyomas by histology and positive hormone receptors, and they seem to have a good long-term prognosis with a small potential for local recurrence.

Smooth muscle tumor of the pleura. A case report and review of the literature

Smooth muscle tumors of the serosal membranes are extremely rare and have received little attention in the literature. To the best of our knowledge, only 1 published series of 5 pleural smooth muscle neoplasms has been published to date. We describe a primary pleural neoplasm with smooth muscle differentiation documented by light microscopy, immunohistochemistry, and electron microscopy. This tumor originated in the parietal pleura in a 32-year-old white man and was diagnosed incidentally by chest radiography; the diagnosis was confirmed by magnetic resonance imaging and biopsy. Four years later, the tumor was noted to have increased in size and disseminated into the chest wall as a separate circumscribed mass located in the pectoral muscle. Both masses were resected and diagnosed as smooth muscle tumors. We conclude that smooth muscle tumor of the pleura is a well-defined entity with a low, but definite malignant potential; therefore, we recommend complete resection and long-term follow-up for all patients.

Immunohistochemical spectrum of GISTs at different sites and their differential diagnosis with a reference to CD117 (KIT)

Gastrointestinal (GI) stromal tumor (GIST) is the designation for the major subset of GI mesenchymal tumors and encompasses most tumors previously classified as GI smooth muscle tumors. Although GISTs typically express CD117 (KIT), often express CD34, and sometimes express alpha-smooth muscle actin (SMA), the relative frequency of these markers has not been characterized in large series of GISTs of different sites, and the CD117 expression has not been fully characterized in intra-abdominal tumors. In this study, we immunohistochemically analyzed 292 GISTs throughout the GI tract, including omentum and mesentery, and compared the immunoreactivities with 211 other tumors that may enter in the differential diagnosis. GISTs were defined in this study as CD117-positive primary spindied or epithelioid mesenchymal tumors of the GI tract, omentum, or mesentery. The CD34 positivity of GISTs varied from 47% in small bowel to 96 to 100% in rectum and esophagus, whereas SMA expression showed the opposite patterns and was most frequent in the GISTs of small bowel (47%) and rarest in the GISTs of rectum and esophagus (10-13%). Desmin was seen only occasionally. S100 positivity was rare but was seen most frequently in small intestinal GISTs (15%). True leiomyomas from esophagus, muscularis mucosae of colorectum, and pericolic leiomyomas similar to uterine leiomyomas were negative for CD117 and CD34 and positive for SMA and desmin (46 of 46). Inflammatory fibroid polyps of stomach and small intestine were negative for CD117 but were often positive for CD34 (6 of 8) and variable for SMA (3 of 8). Inflammatory myofibroblastic tumors involving gastric or colonic wall were negative for CD117 but some showed CD117-positive endothelia. GI schwannomas were all negative for CD117 and positive for S100 protein (11 of 11). Extremely focal CD117 positivity was seen in the neoplastic cells of some retroperitoneal leiomyosarcomas and liposarcomas. Among other CD117-positive tumors were intestinal metastatic melanomas (8 of 11) and extraskeletal Ewing's sarcomas (5 of 11), two of which were abdominal. In conclusion, strong CD117 expression defines most primary GI mesenchymal tumors as GISTs, which show different patterns for CD34 and SMA in various parts of the GI tract. Some unrelated CD117-positive tumors (melanomas, Ewing's sarcomas) should not be confused with GISTs.

Epithelioid sarcoma of the penis: report of an unusual case and review of the literature

Epithelioid sarcoma is a rare, slowly growing soft tissue tumor that uncommonly involves the penis, with only 11 previously reported cases. We present a case of penile epithelioid sarcoma in a 39-year-old man that mimicked Peyronie's disease, which was diagnosed 13 years following initial presentation. Preoperative magnetic resonance imaging showed multiple peripherally enhancing low signal intensity nodules involving the corpora cavernosa bilaterally. Following penectomy, histologic examination showed the typical features of epithelioid sarcoma, with a prominent pseudogranulomatous pattern. Immunohistochemically, the neoplastic cells demonstrated strong and diffuse staining for cytokeratins (AE1/AE3 and CAM 5.2), vimentin, epithelial membrane antigen, and CD34. Stains for S-100 protein, desmin, smooth muscle actin, and CD31 were negative. Electron microscopy demonstrated abundant intracytoplasmic intermediate filaments, scattered tonofilaments, and interdigitating filopodia. The present study is the first to describe magnetic resonance imaging and comprehensive immunohistochemical findings in penile epithelioid sarcoma. The majority of cases reported in the literature have demonstrated features similar to those typically found in epithelioid sarcoma involving the distal extremities. Consideration of epithelioid sarcoma in the differential diagnosis of a penile nodule or obstructive urinary symptoms may lead to early diagnosis and treatment.

Immunohistochemical detection of cytokeratin and epithelial membrane antigen in leiomyosarcoma: a systematic study of 100 cases

Although 'aberrant' expression of the epithelial markers, cytokeratin (CK) and epithelial membrane antigen (EMA), in leiomyosarcoma has been described previously, there has not been a study of this phenomenon with clinicopathological correlation in a large series of lesions at different anatomical sites. We investigated systematically the immunohistochemical reactivity for CK and EMA in 100 cases of leiomyosarcoma. CK and EMA were positive in 38% and 44% of the cases, respectively. Although staining was usually focal, extensive immunoreactivity was observed in 11% with CK and 6% with EMA. There was no correlation between immunoreactivity for CK and EMA in leiomyosarcomas and non-neoplastic smooth muscle at the same location. Immunoreactivity for CK and EMA was not correlated with the location, age, sex, histological grade, or histological features, except for more frequent EMA positivity in vascular and uterine tumors than in soft tissue cases. These results indicate that CK and/or EMA-positive leiomyosarcomas do not have distinctive clinicopathological features differing from those of negative cases. However, the considerable frequency of immunoreactivity for these epithelial markers in leiomyosarcoma, occasionally with diffuse and strong immunopositivity, should be recognized as a potentially serious diagnostic pitfall in the differential diagnosis of other malignant spindle cell neoplasms.

The pathology of uterine smooth muscle tumors and mixed endometrial stromal-smooth muscle tumors: a selective review with emphasis on recent advances

This review focuses on the pathology of uterine smooth muscle tumors (SMTs), with a particular emphasis on those studies published in the past 15 years that have expanded our knowledge of these tumors which still present diagnostic challenges for the pathologist. Leiomyoma variants, leiomyosarcoma, SMTs of low or uncertain malignant potential, epithelioid SMTs, SMTs with unusual growth patterns, and mixed endometrial stromal-SMTs are discussed.

Multilocular cystic epithelioid leiomyoma of the uterus with focal lymphangioma-like pattern: report of a case with immunohistochemical study

We report a rare case of epithelioid leiomyoma of the uterus presenting as a multilocular cystic mass containing clear fluid. The histologic basis of cysts was the diffuse intratumoral cystic degeneration. Histologically, the presence of numerous cystic cavities of variable size raised the possibility that vascular abnormalities, such as hemangioma, lymphangioma, and diffuse cavernous angiomatosis, could be associated with epithelioid leiomyoma. An immunohistochemical study using endothelial cell and basement membrane markers, was helpful in excluding the vascular nature of the cystic cavities and revealed an unexpected focal lymphangioma-like pattern as a peculiar component of tumor.

Unusual dural and skull-based mesenchymal neoplasms: a report of four cases

Dural and skull-base mesenchymal neoplasms other than meningiomas are rare. We report four such tumors, some of which are uncommon even in nonintracranial sites, in three adults and one child. The adult tumors consisted of a synovial sarcoma of the third ventricle region in a 19-year-old woman, a leiomyoma of the suprasellar region in a 57-year-old woman, and an Epstein-Barr virus (EBV)-associated smooth muscle tumor of the cavernous sinus in a 35-year-old woman with acquired immunodeficiency syndrome (AIDS). The pediatric tumor was an EBV-associated leiomyosarcoma of the left dural transverse sinus in a 14-year-old girl with common variable immunodeficiency syndrome. All tumors were thought to be primary in their dural or skull-base locations. The two EBV-associated smooth muscle tumors in immunocompromised patients expand the locations for EBV-associated smooth muscle tumors to dural and skull-base sites, the synovial sarcoma is unique to the intracranial space, and the sellar leiomyoma represents the third reported sellar smooth muscle tumor.

Frequent expression of bcl-2 protein in solitary fibrous tumors

The distinction of solitary fibrous tumors from histologically similar neoplasms is often difficult because they rarely occur at a variety of extrapleural sites. CD34 immunoreactivity has recently been recognized to be an adjunct for the diagnosis of solitary fibrous tumors. However, it is now known that CD34 staining is not entirely specific for this entity. We evaluated 23 solitary fibrous tumors and 54 other spindle cell tumors often considered in the differential diagnosis for immunoreactivity using monoclonal antibodies directed against bcl-2 protein, which protects cells from apoptosis and CD34. The patients with solitary fibrous tumors comprised 11 men and 12 women, ranging in age from 35 to 85 years (mean, 57.6 years). Fourteen tumors arose in the pleura, four in the retroperitoneum, three in the superficial soft tissue and one each in the mediastinum and uterine cervix. Nineteen of 23 solitary fibrous tumors (83%), irrespective of tumor site, demonstrated diffuse cytoplasmic staining for bcl-2 protein. bcl-2 immunoreactivity was also observed in five of seven neurofibromas (71%), eight of 10 synovial sarcomas (80%) and one of three spindle cell lipomas (33%). CD34 immunoreactivity was present in all but one solitary fibrous tumor (96%), seven of seven neurofibromas (100%), three of three spindle cell lipomas (100%), five of five dermatofibrosarcomas (100%), three of three hemangiopericytomas (100%) and two of seven malignant fibrous histiocytomas (29%). To date, most of the pleural and extrapleural cases have not shown aggressive features. We suggest that bcl-2 protein can be used together with CD34 in the diagnosis of solitary fibrous tumor to distinguish this entity from other spindle cell neoplasms.

Epithelioid smooth-muscle tumors of the uterus: a clinicopathologic study of 18 patients

Epithelioid smooth-muscle tumors of the uterus are uncommon neoplasms for which prognostic factors have not been well established. A retrospective follow-up study of 18 uterine epithelioid smooth-muscle tumors was performed. Patients ranged in age from 27 to 83 years (mean, 45 years) and were separated into three groups based on the nuclear grade of the epithelioid tumor cells. Two tumors had grade 1 nuclei; both were examples of intravenous leiomyomatosis. They had highest mitosis counts of 1 and 3 mitotic figures (MF)/10 high-power fields (HPF), no tumor cell necrosis was found, and both patients were alive with no evidence of disease at 64 and 5 months' follow-up. Ten tumors had grade 2 nuclei. All had highest mitosis counts of 0 to 3 MF/10 HPF, except one (5 MF/10 HPF). Tumor cell necrosis was absent in nine and only one had an infiltrative border. Tumor size ranged from 1.5 to 14 cm. Two tumors contained pleomorphic ("symplastic") multinucleated giant cells similar to those seen in bizarre leiomyomas. All nine patients with follow-up were alive with no evidence of disease 5 to 203 months postoperatively (median, 74 months). One patient had also received adjuvant radiation therapy. Six tumors had grade 3 nuclei. Highest mitosis counts of 4 to 9 MF/10 HPF were found in five; one had 1 MF/10 HPF. Maximum tumor size ranged from 4.5 to 13 cm. Two had tumor cell necrosis, and two had an infiltrative border. Two of these patients died of tumor 11 and 132 months postoperatively. The former had widespread metastases at initial surgery (stage IVb); the latter patient (stage I) developed the first of seven tumor recurrences 3 years postoperatively. Both patients had also received adjuvant chemotherapy. Of the remaining four patients, two were alive with no evidence of disease at 48 and 83 months, one was alive (tumor status unknown) at 28 months, and one was lost to follow-up. Based on our findings and those in the literature, we conclude that uterine smooth-muscle tumors with a predominance of epithelioid cells are extremely uncommon and metastasize infrequently. No single histologic feature is predictive of metastatic potential. Clinically malignant tumors (i.e., epithelioid leiomyosarcomas) typically have the combination of significant nuclear atypia (either grade 2 or grade 3 nuclei) and some mitotic activity (usually at least 3 to 4 MF/10 HPF); most also have tumor cell necrosis.

Solitary fibrous tumor of the nasal cavity and orbit

Solitary fibrous tumors (SFT) are rare spindle cell neoplasms generally associated with the serosal surface, especially the pleura. Two SFT are reported arising in the nasal cavity and orbit, occurring in a 33 year old female and a 21 year old male, respectively. The lesions lacked the characteristic features of other recognized neoplasms that occur in these regions. Immunohistochemically, the tumors cells were diffusely and strongly positive for vimentin and CD34 and some or many tumor cells expressed neuron-specific enolase and Leu-7. Ultrastructurally, the tumor cells showed no distinct features although they were suggested to be primitive mesenchymal or fibroblast-like cells. Both tumors were diploid by flow cytometry. The two patients have had benign clinical courses with limited follow-up. Our findings suggest that SFT is of mesenchymal cell origin and support another location for SFT, indicating additional evidence against mesothelial origin. SFT should be included in the differential diagnosis of spindle cell tumors arising in the nasal cavity and orbit.

CD34 expression by gastrointestinal tract stromal tumors

Gastrointestinal stromal tumors (GISTs) are neoplasms arising in the wall of the gastrointestinal tract that frequently show evidence of smooth muscle differentiation, either by their appearance alone or by immunohistology. A significant number of these neoplasms fail to react with any markers of muscle differentiation, however. A subset of these neoplasms have epithelioid features, and the presence of these features can give rise to confusion with other neoplasms, such as carcinomas and melanomas. Here we show that the CD34 monoclonal antibody My10 reacts with 19 of 23 (83%) of these lesions, including both those with and without epithelioid features. Five of 10 epithelioid and one of 13 spindled neoplasms lacked detectable muscle-specific actin (MSA), smooth muscle actin (SMA), and desmin; all six were CD34 reactive. Immunoblotting experiments show that the antigen on these stromal neoplasms has a molecular weight identical to that found on hematopoietic cells. The frequency and intensity of the reactivity of GISTs with anti-CD34 antibodies are distinctly higher than those reported for smooth muscle neoplasms of soft tissue and myometrium. This reactivity can be a useful adjunct in the diagnosis of difficult cases, especially in those exhibiting epithelioid morphology.