Immunohistochemical and electron microscopic findings in benign fibroepithelial vaginal polyps

Fibroepithelial Stromal Polyp of the Vulvovaginal Region as Part of the RB1 Family of Tumors: Friend or Foe?

Fibroepithelial stromal polyps (FSPs) are benign mesenchymal lesions occurring in the vulvovaginal region. Following the identification of loss of Retinoblastoma 1 (RB1) on immunohistochemical staining in routine practice, we stained a series of FSPs and performed additional fluorescence in situ hybridization (FISH) and copy number variation (CNV) sequencing to detect losses/deletions in the Retinoblastoma transcriptional corepressor 1 (RB1) gene. Fifteen FSP cases were stained for RB1, and subsequently, 9 cases were examined by FISH to detect a loss of RB1 (13q). Next, CNV sequencing was performed to assess genomic alterations. The mean age of the patients was 50 years. Loss of RB1 expression on immunohistochemistry was seen in 13 cases, and heterogeneous RB1 staining in the remaining 2 cases. FISH showed deletion of RB1 in all of the cases. CNV sequencing failed in almost all cases due to a low tumor content. Based on our findings, we hypothesize that FSPs are part of a spectrum of genetically related lesions, namely the 13q/RB1 family of tumors (which includes pleomorphic fibromas and spindle cell/pleomorphic lipomas). Due to the clinical, morphologic, and molecular overlap, we suggest that FSPs are pleomorphic fibromas occurring in the specialized stroma of the genital region.

Differential expression of nuclear hormone receptors by dendritic cell subsets in human vaginal mucosa and skin

Nuclear hormone receptors (NHRs) expressed by dendritic cells (DCs), the major immune inducers and regulators, could play important roles in host immunity. Assessment of NHRs expressed by DCs in the vaginal mucosa (VM), in comparison with those expressed by DCs in other tissues, will thus help us understand the immunology of human vagina. This study identified 16 NHR transcripts that are differentially expressed among 8 different antigen-presenting cell (APC) subsets isolated from human VM, skin, and blood. The expression profiles of NHRs were largely tissue specific. VM APCs expressed increased levels of LXRA, RXRA, ESRRA, ESRRAP2, and PPARG, whereas skin and blood APCs expressed increased levels of NURR1, NOR1 and RARA. Of interest, female sex hormone receptors, ESR1 and PGR, were found to be mainly expressed by non-APC cell types in the VM; ESR1 by HLA-DR⁺CD34⁺ and PGR by HLA-DR^- cells. ERα and PR were expressed by vimentin⁺ cells in the VM, but not in human skin. ERα, but not PR, was also expressed in CD10⁺ cells in the lamina propria of VM. In conclusion, NHR expression by APC subsets is tissue- and cell type-specific. Future studies on the roles of individual NHRs expressed by different cell types, including DC subsets, in the human VM are warranted.

Cell type-specific expression of estrogen and progesterone receptors in the human vaginal mucosa

Female sex hormones affect the immune response in the lower female genital tract. To understand their mechanisms of action, it is essential to define cell types expressing estrogen receptor (ER) and/or progesterone receptor (PR) in the human vaginal mucosa (VM). Here, we report that none of the dendritic cell (DC) subsets in the human VM expressed ERα or PR in situ. However, they were capable of expressing ERα, but not PR, after in vitro culture of the whole VM tissues. Similarly, ERα and/or PR expression by T cells in the VM tissues was also inducible rather than constitutive. In contrast, ERα and/or PR were constitutively expressed in HLA-DR^- non-immune cell types (vimentin⁺, desmin⁺, or CD10⁺). These new findings will help us understand the mechanisms of action of female sex hormones in the modulation of immune response in the human VM and lower female genital tract.

Mesenchymal lesions of the vulva

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

MyoD1 expression in fibroepithelial stromal polyps

Fibroepithelial stromal polyps (FESPs) are benign polypoid mesenchymal lesions thought to arise from desmin-positive specialized stromal cells of the female genital tract. Although most cases are easily diagnosed by morphology alone, the morphology of FESPs is variable and in some instances can contain hypercellular stroma with numerous atypical desmin-positive cells, simulating botryoid embryonal rhabdomyosarcoma (ERMS). Recently, we encountered a cellular FESP showing desmin expression as well as nuclear immunoreactivity for the skeletal muscle-associated transcription factor MyoD1. Although these lesions are widely known to express desmin, there are very few studies examining expression of the more specific markers of skeletal muscle differentiation, myogenin and MyoD1. The aim of our study was to examine desmin, MyoD1, and myogenin expression in a series of 25 FESPs. Of the 25 cases, desmin expression was present in 23 (92%), at least focal MyoD1 expression was present in 10 (40%), and all cases were negative for myogenin. Follow-up data were available for all 25 cases, and none recurred or behaved in a malignant fashion. Awareness of this potential immunohistochemical pitfall and careful morphologic evaluation should allow for the confident distinction of MyoD1-positive FESP from botyroid ERMS in almost all instances.

Multinucleated stromal giant cells in the gastroesophageal junctional and gastric mucosa: a retrospective study

Background

Atypical multinucleated stromal giant cells (MSGCs) are occasionally encountered in the esophagogastric mucosa. This study aims to investigate the origin and clinical association of MSGCs in the upper gastrointestinal tract.

Methods

Three hundred sixty-one contiguous biopsies and 1 resection specimen from the stomach and gastroesophageal junction (GEJ) were identified from archives for morphologic and immunohistochemical studies.

Results

MSGCs were identified in 22 cases (6%: 7 gastric, 15 GEJ). Patients’ average age was 53 years. There was no sex predilection. 77% cases had only 1 or 2 MSGCs per 10 high power fields. MSGCs were located in the lamina propria of the gastric or GEJ mucosa, with an accentuation in the subepithelial zone. The median number of nuclei in a MSGC was 5 (ranging from 3 to 16). The nuclei were touching/overlapping, often arranged into “wreath”, “caterpillar”, or “morula” configurations. MSGCs expressed smooth muscle actin, desmin, while negative for cytokeratin AE1/3, CD68, S100, chromogranin, and CD117. The most common clinical history was epigastric pain, gastroesophageal reflux, and Barrett esophagus. The most common associated pathologic diagnoses included reactive (chemical) gastropathy (71% gastric biopsies) and gastroesophageal reflux (73% GEJ specimens).

Conclusions

MSGCs in the esophagogastric mucosa show smooth muscle/myofibroblast differentiation by immunohistochemistry and likely represent a reactive/reparative stromal reaction associated with gastroesophageal reflux and reactive (chemical) gastropathy.

Myogenin expression in vulvovaginal spindle cell lesions: analysis of a series of cases with an emphasis on diagnostic pitfalls

AIMS

Myogenin (myf4) is a nuclear transcription factor that is considered to be a sensitive and highly specific marker for skeletal muscle differentiation. Following the identification of focal strong nuclear staining with myogenin in two fibroepithelial polyps of the lower female genital tract (the index cases), we stained a series of vulvovaginal spindle cell lesions with this marker in order to investigate how widespread myogenin staining is in these lesions.

METHODS AND RESULTS

Fibroepithelial polyps (n = 13), other vulvovaginal mesenchymal lesions (n = 21) and vulval or vaginal spindle cell squamous carcinomas (n = 4) were stained for myogenin. Apart from the index cases, all of the other cases were negative, except for one vaginal spindle cell squamous carcinoma, which showed focal weak nuclear immunoreactivity. Ten of 12 embryonal rhabdomyosarcomas of the lower female genital tract were myogenin-positive, as was a single vaginal rhabdomyoma.

CONCLUSIONS

Our study illustrates that focal myogenin immunoreactivity occurs uncommonly in fibroepithelial polyps of the lower female genital tract. This may result in diagnostic confusion and misdiagnosis as a skeletal muscle neoplasm, especially the sarcoma botryoides variant of embryonal rhabdomyosarcoma.

Immunohistochemical Markers of Value in the Diagnosis of Mesenchymal Lesions of the Female Genital Tract

Pure mesenchymal tumors may occur anywhere in the female genital tract, but they are most common in the uterine corpus, leiomyoma being by far the most prevalent. These tumors, and other uncommon mesenchymal lesions within the uterine corpus and elsewhere in the female genital tract, may result in several diagnostic problems. Morphology remains paramount and, in most cases, an unequivocal diagnosis can be made based on examination of the hematoxylin and eosin stained sections, combined with an appreciation of the clinical and gross pathologic features. In difficult cases, immunohistochemistry can significantly contribute to the final diagnosis. In this article, the immunohistochemistry of neoplastic and nonneoplastic mesenchymal lesions of the female genital tract is discussed site by site, concentrating on markers that are of value in diagnosis and in differential diagnosis. The immunophenotype of mixed epithelial and mesenchymal neoplasms and pure epithelial neoplasms with a component of spindle cells is discussed, where appropriate, because these can enter into the differential diagnosis of a pure mesenchymal lesion.

Fibroepithelial polyp of the prepuce: A rare complication of long-term condom catheter usage

External urinary drainage devices are in wide clinical uses. There are only a few reports of complications from improper use of condom catheters. We present a case of fibroepithelial polyp of the penis, due to long-term usage of condom catheter. The lesion affected the ventral aspect of the penis. He was successfully treated with wide local excision. The histopathological diagnosis was a fibroepithelial polyp.

Cutaneous pseudosarcomatous polyp: a recently described lesion

Three cases of cutaneous pseudosarcomatous polyp, a lesion recently described in the dermatopathology literature, are reported here. These benign proliferations display dramatic cytologic pleomorphism, but despite their disquieting morphological features, they have behaved in a benign fashion to date. All 3 lesions in this study were clinically innocuous, with 1 having been present for 1 year and another for 2 years. The first lesion arose on the back of a 30-year-old man, the second on the nasal columella of a 65-year-old woman, and the third on the back of a 91-year-old woman. All 3 had the typical architecture of a fibroepithelial polyp (acrochordon) with widely separated stellate cells occupying a myxoid to collagenous stroma. Markedly pleomorphic stellate cells were widely dispersed, with an increased density of atypical cells beneath the epidermis and in small foci of adipose tissue in 1 case. Multinucleated cells, some with a floret-type configuration, were also observed. One of the polyps demonstrated focal mild hyalinization of vessel walls. Only rare mitotic figures were identified in 2 cases, but 1 showed atypical forms. Immunohistochemically, the atypical cells reacted diffusely for vimentin and variably for CD34 and factor XIIIa, but they lacked smooth muscle actin and desmin. Cutaneous pseudosarcomatous polyps can be added to the list of pathologic entities with symplastic or pseudomalignant features.

Tubulo-squamous Polyp

We report 10 cases of a morphologically distinct vaginal polyp which has hitherto not been characterized. The polyps occurred in women aged 39 to 78 years (most were postmenopausal) and were from 1.0 to 3.0 cm. Most of whose location is known to us were in the upper vagina. Histologically, all the polyps were remarkably similar and composed of well-circumscribed expansile nests of epithelial cells embedded in a hypocellular fibrous stroma. The epithelial elements, which were morphologically bland, were predominantly glycogenated or nonglycogenated squamous in type but small tubules were present at the periphery of some of the nests in all cases. Some of the squamous nests exhibited central necrosis with or without calcification and, in 3 cases, some contained keratin pearls. In 3 cases, a few tubules unassociated with squamous elements were present. In 3 of 4 cases tested, the cells lining the tubules were positive with prostatic acid phosphatase and in 2 of 4 with prostate-specific antigen. The epithelial elements reacted with broad-spectrum cytokeratins and cytokeratin 7 but the mesenchymal component was negative. The squamous elements were estrogen receptor positive and the mesenchymal component estrogen and progesterone receptor positive. The histologic features of this polyp, which we term "tubulo-squamous polyp of the vagina," are constant and distinctive and differ from other polyps and from mixed tumor of the vagina. Several cases reported in the literature as vaginal mixed tumor or Brenner tumor are likely examples of this entity. Possible theories of histogenesis include a Mullerian origin, derivation from mesonephric remnants or derivation from urogenital sinus-derived epithelium. Positive staining in some cases with prostatic acid phosphatase and prostate-specific antigen raises the possibility of ectopic prostatic tissue, although the overall appearance is different from that entity, or derivation from paraurethral Skene glands, the female equivalent of prostatic glands in the male.

Multinucleated stromal giant cells in colonic lamina propria

AIMS

Multinucleated stromal giant cells occur in the anus, genitals and many other organs. They resemble myofibroblasts, react to local injury and are found incidentally or in association with various lesions. They have only rarely been reported to occur in the colon. The aim was to firmly establish their existence in colorectal lamina propria.

METHODS AND RESULTS

Specimens from one hundred biopsies taken from throughout the colon (70%) and rectum (30%) were retrospectively reviewed. Multinucleated stromal giant cells occurred in 23 specimens (23%), were pancolonic but surprisingly spared rectal mucosa (0%). Multinucleated stromal giant cells occurred in both normal mucosa and abnormal mucosa and appeared to be larger and more numerous in abnormal mucosa than in normal mucosa. Specimens with tubular adenomas appeared to have strikingly abundant multinucleated stromal giant cells with large numbers of nuclei. Immunohistochemistry and ultrastructural examination showed features consistent with myofibroblastic differentiation.

CONCLUSIONS

We have firmly established the existence of multinucleated stromal giant cells in colonic lamina propria and confirm their myofibroblastic differentiation. They may be more common in abnormal mucosa and particularly prominent in the setting of tubular adenoma. Absence of rectal multinucleated stromal giant cells may represent a microanatomical difference between the colon and rectum.

Symplastic hemangioma: report of two cases

Symplastic hemangioma is characterized by degenerative atypia of vascular smooth muscle and interstitial cells within a pre-existing vascular lesion with minimal endothelial cell atypia. We describe an additional two cases of this distinctive but poorly recognized entity. On histology, both lesions revealed a cirsoid aneurysm-type appearance with thick-walled and variably dilated blood vessels. The vascular endothelial cells showed mild nuclear hyperchromasia with no multilayering or mitoses. The atypical cells, either located within the vascular smooth muscle wall or within the interstitium, were spindle or epithelioid with varying degrees of hyperchromasia, nuclear enlargement, pleomorphism, and multinucleation. Perivascular hemorrhage, vascular thrombosis, and focal papillary endothelial hyperplasia were uniformly present. The variably fibrous to edematous stroma showed hemosiderin deposits and a mononuclear inflammatory infiltrate. Clusters of adipocytes were present within the superficial dermis. Rare atypical mitoses and occasional bizarre lipoblast-like stromal cells were identified in one tumor. Immunohistochemistry showed focal smooth muscle actin positivity in the pleomorphic cells of the vascular walls. CD68 and CD34 stained occasional stromal cells in the interstitial location. Both the cases showed no recurrence. The bizarre cytologic changes are interpreted as degenerative in nature and probably akin to that observed in ancient schwannoma and uterine symplastic leiomyoma.

Lymphedematous fibroepithelial polyps of the glans penis and prepuce: a clinicopathologic study of 7 cases demonstrating a strong association with chronic condom catheter use

This report describes an underrecognized entity of the penis that is associated with chronic condom catheter use and phimosis. Our study group consisted of 7 patients who presented with polypoid or cauliflower-like masses that involved the glans penis or prepuce and that ranged in size from 2 to 7.5 cm in greatest dimension (median size, 2.5 cm). The majority of lesions affected the ventral surface of the glans, near the urethral meatus. The patients ranged in age from 25 to 58 years (median age, 40 years) at the time of initial surgical resection. The preoperative duration of the lesions ranged from 6 months to 10 years. Five patients had a history of long-term condom catheter use (duration: 5 to 21 years), and 1 patient had paraphimosis. The background history for 1 patient is unknown. Histologically, all specimens had a polypoid configuration and a keratinizing squamous epithelial surface. The underlying stroma was notably edematous, and there was vascular dilation of preexisting vessels, and in many instances, a focal mild small vessel proliferation. The stroma had mildly to moderately increased cellularity with mononucleated and multinucleated mesenchymal cells. A mild inflammatory infiltrate was often present. Two cases were examined with immunohistochemistry, and the stromal cells had limited immunoreactivity for muscle-specific actin, alpha-smooth muscle actin, and desmin and had no reactivity for S100 protein or CD34. Surgical intervention was local in all instances. Follow-up information was available for 5 of the 7 patients (71%), with a mean follow-up interval of 11 years 4 months. Two patients developed a local recurrence of the process at intervals of less than 1 years and 3 years 7 months. Both recurrent lesions were also managed by local excision.

Immunohistochemistry in gynecological pathology

Although the majority of diagnoses in gynecological pathology are established on examination of routine hematoxylin and eosin stained sections, additional tests are occasionally required. Immunohistochemistry is widely used to provide additional diagnostic information in problematic cases. This review touches on some of the basics of the procedure, presents an example immunohistochemical panel, and discusses some of the most common immunohistochemical markers used in diagnostic gynecological pathology. Differential diagnostic problems and relevant immunohistochemical stains for the vulva, vagina, cervix, uterus, and ovary are also addressed.

CD34+ stromal cells and hyalinized vascular changes in the anal fibroepithelial polyps

AIMS

To elucidate the pathogenesis of the anal fibroepithelial polyp, we examined surgically resected lesions histopathologically.

METHODS AND RESULTS

Twenty-seven surgically resected anal fibroepithelial polyps were investigated histologically with an additional immunohistochemical examination using anti-CD34. For a control study, the surgical specimens of the anal canal showing non-polypoid lesions, obtained from haemorrhoidectomy (18 specimens) and rectectomy (five specimens) due to rectal cancer without anal canal involvement, were also analysed. We demonstrated characteristic spindle or stellate cells immunohistochemically positive for CD34 in the anal fibroepithelial polyps (24/27, 89%). The number of CD34+ cells was statistically related to the size of anal fibroepithelial polyps, although CD34+ stromal cells were recognized in the non-polypoid anal submucosa and haemorrhoids. We also found hyalinized vascular changes in the base of six anal fibroepithelial polyps examined. These features were not detected in the non-polypoid anal canal.

CONCLUSIONS

An increase in CD34+ stromal cells may play a role in the enlargement of anal fibroepithelial polyps. CD34+ stromal cells are suggested to be distinctive mesenchymal cells with a capability for tissue repair and overgrowth. The vascular impairment could be secondary change associated with localized tissue damage by abnormal traction.

Superficial cervicovaginal myofibroblastoma: fourteen cases of a distinctive mesenchymal tumor arising from the specialized subepithelial stroma of the lower female genital tract

The clinicopathologic features and immunohistochemical profiles of 14 cases of a distinctive mesenchymal tumor that arises in the superficial lamina propria of the cervix and vagina and is histologically distinguishable from mesodermal (fibroepithelial) stromal polyp, including the cellular (pseudosarcomatous) variant, angiomyofibroblastoma, aggressive angiomyxoma, and other well-recognized lesions that occur in this location, are described. The lesions presented as a polypoid (n = 10) or nodular (n = 4) mass in the vagina (n = 12) or cervix (n = 2) of women ranging in age from 40 to 74 years (median, 58 years). The tumors were subepithelial in location, were well circumscribed, and ranged in size from 1 to 6.5 cm. (mean, 2.7 cm). Microscopically, the process was moderately to highly cellular and composed of relatively bland spindled and stellate-shaped mesenchymal cells embedded in a finely collagenous stroma that was punctuated by myxoid and edematous foci in 9 cases. The lesions characteristically had a multipatterned architecture with tumor cells focally assuming a lacelike/sievelike growth pattern in the more stroma-rich areas of the tumor and a vague fascicular growth pattern in the more cellular foci. Mitotic activity was minimal, and no atypical mitotic figures were identified. The tumors were immunoreactive (in decreasing order of relative strength) for vimentin (5 of 5 cases), estrogen (10 of 10 cases), and progesterone (10 of 10 cases) receptors, desmin (13 of 13 cases), CD34 (11 of 13 cases), alpha-smooth muscle actin (5 of 11 cases), and muscle-specific actin (2 of 8 cases). The desmin and CD34 antibodies highlighted the interconnecting, dendritic processes associated with many of the tumor cells. No immunoreactivity was detected for S100 protein, epithelial membrane antigen, or keratins. Follow-up data for 11 patients (range, 1 to 20 years; median, 4 years) showed no recurrence or metastasis after local excision. The term "superficial cervicovaginal myofibroblastoma" is proposed because it reflects the distinguishing features of this benign, relatively site-specific mesenchymal tumor. The process probably arises as a neoplastic proliferation of hormonally responsive mesenchymal cells native to the unique subepithelial stromal layer normally found through the endocervix and vulva of adult women.

Multinucleated stromal cells of the anal mucosa: a common finding

AIMS

To document the presence, morphology, immunophenotype and ultrastructure of multinucleated stromal cells within the anal mucosa and to discuss possible pathogenetic mechanisms for this occurrence.

METHODS AND RESULTS

Multiple sections of normal anal mucosa from 30 abdominoperineal resection specimens were analysed by light microscopic, electron microscopic and immunohistochemical methods. Multinucleated stromal cells were found in 22 cases (73%). They contained two to five nuclei, arranged in a linear fashion or in a rosette or grape-like pattern. They stained positive for vimentin and negative for actin, desmin and oestrogen/progesterone receptors. Ultrastructural examination confirmed their fibroblastic lineage. Mast cells were frequently observed in the immediate vicinity of mono- and multinucleated cells.

CONCLUSIONS

Multinucleated stromal cells are a common occurrence in the normal anal mucosa. They should not be misinterpreted as neoplastic cells. Mast cells may play a role in their morphogenesis.

Cellular pseudosarcomatous fibroepithelial stromal polyps of the lower female genital tract: an underrecognized lesion often misdiagnosed as sarcoma

Fibroepithelial stromal polyps of the vulvovaginal region are benign lesions that, when bland or hypocellular, are readily recognized. However those that exhibit bizarre cytomorphology, atypical mitoses, or hypercellularity, raising the possibility of malignancy, continue to be underrecognized. The authors reviewed a series of fibroepithelial stromal polyps to characterize further the morphologic features that can lead to a misdiagnosis of sarcoma. A total of 33 of 65 consecutive cases of fibroepithelial stromal polyps retrieved from the authors' consultation files were remarkable for marked hypercellularity (33 of 33), marked cytologic pleomorphism (21 of 33), mitotic counts of more than 10 mitoses per 10 high-power fields (12 of 33), and the presence of atypical mitoses (14 of 33). A total of 16 of 33 lesions had three or more of these features. Important morphologic clues to the diagnosis (shared with usual polyps at this site) were lack of an identifiable lesional margin, extension of abnormal stromal tissue up to the mucosal-submucosal interface, and the frequent presence of individually scattered multinucleate stromal cells, most often located close to the surface epithelium. Immunohistochemically, seven of 12 cases were desmin positive and one of 11 cases were smooth muscle actin positive. The age range of patients was 16 to 75 years (median, 32 years), and 21 patients (64%) were premenopausal. Sites included the vagina (18 of 33), cervix (seven of 33), and vulva (eight of 33). A total of 14 of 33 patients were pregnant, three patients were taking Tamoxifen, and one patient was on oral progesterone. Eight of 33 patients had multiple lesions at the time of presentation, of whom five were pregnant. Clinical follow-up was available in 21 of 33 patients. Three of 21 patients with follow-up had local, nondestructive recurrence. Two of these patients had multiple recurrences. None of the patients followed developed metastases. Cytologic atypia has been a previously recognized feature in these lesions; however, the occurrence of marked stromal cellularity and a mitotic rate of more than 10 mitoses per 10 high-power fields have not been emphasized previously. Moreover, the combination of these features has only rarely been documented. Awareness of the spectrum of histologic features that these lesions can exhibit is crucial in their accurate recognition, thus avoiding potential overtreatment.

Fibroepithelial polyps of the anus: a histologic, immunohistochemical, and ultrastructural study, including comparison with the normal anal subepithelial layer

Fibroepithelial polyps of the anus (FEPA) are relatively common lesions that have attracted little attention. A series of 40 FEPA, together with sections from normal anal mucosa, were studied histologically, histochemically, immunohistochemically, and ultrastructurally. The polyps consisted of myxoid or collagenous stroma covered by squamous epithelium. Stromal cells with two or more nuclei were found in 30 polyps (80%). In five cases (12%) these cells showed atypical nuclear features. All the polyps harboring atypical cells were of large size. Mast cells were frequently present and sometimes intimately related to the stromal cells. Stromal cells stained positive for vimentin and negative for actin. Desmin was expressed in 30% of the cases. Electron microscopic examination confirmed the fibroblastic and myofibroblastic nature of the stromal cells. Examination of the subepithelial connective tissue from the normal anal mucosa showed bizarre multinucleated cells and mast cell infiltration. It is concluded that FEPA are benign lesions characterized by the presence of mononucleated and multinucleated, sometimes atypical stromal cells showing fibroblastic and myofibroblastic differentiation. The morphologic similarity between FEPA and normal anal mucosa supports the hypothesis that FEPA may represent a reactive hyperplasia of the subepithelial connective tissue of the anal mucosa. Mast cells, by means of their fibrogenic, fibrolytic, and angiogenic activities may play an important role in the pathogenesis of FEPA.

Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant

The clinicopathological and immunohistochemical profile of 17 cases of angiomyofibroblastoma (AMF) arising in the genital tract of females is reported. The lesions usually presented as painless masses and were located in the superficial vulvar region (15 cases), canal of Nuck (one case), and perineum (one case) in women ranging in age from 38 to 60 years (median, 46 years). The tumors were well delineated and ranged in size from 2 to 8 cm in greatest dimension. Microscopically, they were composed of spindled and epithelioid mesenchymal cells arranged in cords and nests preferentially arrayed around numerous small to medium-sized vessels. Mitotic activity ranged from 0 to 7 mitoses per 50 high-power fields (HPF) with no abnormal mitotic figures. Minimal nuclear atypia was appreciated. Intralesional fat was present in 12 cases and in two of these cases constituted most of the tumor (lipomatous variant of AMF). Tumor cells expressed vimentin (five of five cases), estrogen receptor protein (six of six cases), progesterone receptor protein (five of six cases), desmin (six of eight cases), CD34 (one of six cases), and smooth muscle actin (one of seven cases). None of the eight women with follow-up of up to 25 years (mean, 7.8 years) after simple excision developed a recurrence. This study confirms the benign nature of AMF, broadens its morphological spectrum to include a lipomatous variant, and proposes an origin from a perivascular stem cell that is capable of myofibroblastic and fatty differentiation.

Urethral caruncle with atypical stromal cells simulating lymphoma or sarcoma--a distinctive pseudoneoplastic lesion of females. A report of six cases

Six urethral caruncles in women aged 32 to 82 (average, 56) years contained atypical stromal cells raising concern for a neoplasm. The atypical cells varied from spindled to round, the latter predominating, and typically had scant cytoplasm. A minority of the cells were binucleated or multinucleated and often had prominent nucleoli. A single mitotic figure was found in the atypical cells in one case. The atypical cells were characteristically present in an edematous background containing numerous inflammatory cells and were focally crowded together in five cases. The differential diagnosis in these cases included a florid reactive proliferation of lymphoid cells, but immunohistochemical stains failed to support a lymphoid nature for the atypical cells and also helped to exclude malignant lymphoma, the neoplasm most often simulated. Because of the invariable additional component of atypical spindle cells resembling those described in the stroma of the lower female genital tract and in polyps in a variety of sites, the round cells likely represent a variant of this atypical mesenchymal cell. Similar round mesenchymal cells have also been documented in the gastrointestinal tract, especially the stomach. Immunohistochemical stains in this series showed them to be positive for vimentin in four of four cases and for alpha smooth-muscle actin in two of four cases. The prominence of atypical round stromal cells in these cases appears to be a distinctive feature of some urethral caruncles. The presence of these cells should not lead to misinterpretation of the lesion as a neoplastic process.

Brief review of the fibronexus and its significance for myofibroblastic differentiation and tumor diagnosis

This brief review details the structure, nature, and distribution of the fibronexus, and discusses its significance for myofibroblastic differentiation and tumor diagnosis. The fibronexus is a cell surface specialization consisting of intracellular actin filaments and extracellular fibronectin filaments associated with subplasmalemmal plaque material. The fibronexus represents an intercellular junction between myofibroblasts, but in particular is a device for providing contact between myofibroblasts and matrix that mediates continuity between intracellular contractile filaments and extracellular matrix proteins. Immunoelectron microscopy in particular has shown that the intracellular filaments contain actin. The extracellular filaments contain fibronectin and collectively form the fibronectin fibril. The plaque probably contains such proteins as vinculin, talin, alpha-actinin, and integrin. Under appropriate biologic development and fixation conditions, the fibronectin fibril of the fibronexus is characterized by and distinguished from lamina by enhanced density, a rigid appearance, failure to adhere closely to the contours of the cell surface (except focally near the plaque material), and a longitudinally filamentous substructure. Confirmation of the presence of a fibronectin fibril may be obtained by the finding of intense cell surface staining with an antifibronectin antibody. Problems in identifying the fibronexus may be encountered, however, due to poor development and fixation, in which case the filamentous substructure may be inapparent. The fibronexus is such a typical feature of and is often so conspicuous in myofibroblasts that it can be regarded as perhaps essential for the interpretation of myofibroblastic differentiation. Structures with a similar appearance have been documented in fundamentally nonmyofibroblastic cells; these include aortic and scleral spur smooth muscle cells and endothelium. Uncertainties remain in the protein composition of the fibronexus, the nature of its contact with the matrix, and its relationship to similar structures seen in nonmyofibroblastic cells. Immunoelectron microscopy provides a potential means of clarifying some of these questions.

The nature of atypical multinucleated stromal cells: a study of 37 cases from different sites

The morphology, immunophenotype and ultrastructure of atypical multinucleated stromal cells in 37 specimens from different anatomical sites were compared. Overall, cellular morphology was similar between sites but nuclear features, immunophenotype and ultrastructure varied and reflected that of adjacent normal mononuclear stromal cells. It is concluded that the atypical multinucleated stromal cells represent a reactive change in the indigenous stromal cells. In all the cases mast cells were seen as a prominent component of the inflammatory infiltrate and many of them were intimately related to the atypical stromal cells. It is suggested that reactive stromal cell changes may relate to an interaction with mast cells.

Fibroepithelial polyps of the vagina: are they old granulation tissue polyps?

AIMS

To study the nature of fibroepithelial polyps of the vagina.

METHODS

Sixty five fibroepithelial polyps of the vagina and 64 granulation tissue polyps diagnosed over 15 years were reviewed histologically.

RESULTS

Cytologically benign multinucleated stromal cells were present in large numbers in 19 of the fibroepithelial polyps of the vagina (FEPV). Only one polyp contained atypical stromal cells, a high mitotic count, and abnormal mitoses and was indistinguishable from a malignant tumour. Immunostaining showed the presence of vimentin and desmin positive mono- and multinucleated stromal cells in FEPV and occasional oestrogen receptor positive nuclei. Desmin positive cells could not be shown in granulation tissue polyps.

CONCLUSIONS

FEPV are common lesions with benign mono- and multinucleated fibroblastic stromal cells in which myoid differentiation is often present. FEPV may develop as a result of a granulation tissue reaction after some local injury of the vaginal mucosa. Hormonal factors may modulate the growth of FEPVs. Delayed differentiation of myofibroblastic cells may explain why granulation tissue sometimes does not contract properly but turns into polyps.

Benign vaginal polyp: a histological, histochemical and immunohistochemical study of 20 polyps with comparison to normal vaginal subepithelial layer

Twenty benign vaginal polyps from 18 patients, together with sections from normal vaginal epithelium, were studied histologically, histochemically using elastic van Gieson stain and immunohistochemically using monoclonal antibodies against vimentin, desmin and actin. The striking finding was the similarity, both histologically and immunohistochemically, of the stroma of vaginal polyps to that of the loose subepithelial layer found in normal vagina. The important difference was the marked degeneration of the elastic tissue, increased number of stellate and giant fibroblasts and subepithelial condensation of fibroblasts in the polyps. These findings support the hypothesis that vaginal polyps may represent a reactive hyperplasia of the loose subepithelial zone of the vaginal wall.

Prosopagnosia

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