Denervation of transplanted porcine lung causes airway obstruction

Lung transplantation can be complicated by a form of small airway obstruction known as bronchiolitis obliterans. We tested the hypothesis that lung denervation causes small airway obstruction in young pigs (10 +/- 1 weeks). Control pigs had an innervated native lobe, and study pigs had either a denervated native lobe or a denervated transplant lobe. Transplanted pigs received standard immunosuppression. At 10 weeks we measured isolated left lobe pulmonary mechanics. Dynamic resistance in both study groups was significantly higher than in the lobectomy group, whereas dynamic compliance in both study groups was significantly lower than in the lobectomy group. No significant difference in resistance or compliance was noted between the transplant and reimplant groups. Histologic changes consistent with rejection were noted in the transplant lobes. We conclude that the small airway obstruction noted in this model is due to operative denervation rather than to immunosuppression or rejection.

Sinonasal malignant melanoma. A clinicopathologic and immunohistochemical study of 14 cases

The clinical, light microscopic, and immunohistochemical features of 14 sinonasal malignant melanomas were studied to show their diverse morphologic appearance and distinction from therapeutically more amenable neoplasms that occur in this region. The tumors arose in 6 men and 8 women (median age, 70 years). Eleven patients died of disease 7 to 44 months (median, 18 months) after diagnosis. The absolute median survival time was 18.5 months (range, 7 to 44 months). The predominant microscopic appearance was categorized as small blue cell in eight cases, spindle cell in three cases, epithelioid in two cases, and pleomorphic in one case. Eight tumors had multiple patterns. Five sinonasal malignant melanomas had theque-like growth, five had junctional change, and 10 contained at least rare melanin pigment. Fourteen, 13, and 12 sinonasal malignant melanomas were immunoreactive with anti-vimentin, HMB45, and anti-S100 protein antibodies, respectively. One epithelioid tumor positive for vimentin, S100, and HMB45 also contained scattered epithelial membrane antigen-positive and cytokeratin-positive cells, which emphasizes the need for a battery of stains to distinguish sinonasal malignant melanoma from carcinoma. All tumors were negative for leukocyte common antigen, muscle-specific actin, and synaptophysin. Diffuse immunopositivity for vimentin, S100 protein, and HMB45 allows distinction of sinonasal malignant melanomas from histologically similar neoplasms.

The mystique of the mistake. With proposed standards for validating proficiency tests in anatomic pathology

Variability in classification in anatomic pathology does not necessarily indicate that a mistake has been made. It is usually an artifact, created when pathologists choose a single category from among two or more justifiable alternatives. This is most common when standard classifications with uniform terminology are not used. It also can occur when classification systems are not constructed so as to insure mutual exclusivity of categories. It is proposed that a proficiency test in anatomic pathology should not be considered scientifically valid until a professional organization primarily concerned with anatomic pathology has endorsed its proposed classification system as having categories that are close to 100% mutually exclusive in the hands of expert pathologists not involved in developing the system. All possible precautions should be taken to insure that the "right answers" for any proficiency test are generated in a way that excludes the possibility of multiple justifiable alternatives.

Spindle cell mural nodules in cystic ovarian mucinous tumors. A clinicopathologic and immunohistochemical study of five cases

We studied five cystic ovarian mucinous tumors with spindle cell mural nodules to define their histologic and immunohistochemical properties. Three of these mural nodules consisted of carcinomatous nests surrounded by highly pleomorphic polygonal and spindle cells. There were transition zones between the pleomorphic cells and the cell nests. In all three cases, both cell populations coexpressed cytokeratin and vimentin, suggesting a diagnosis of anaplastic carcinoma. A fourth nodule consisted of moderately differentiated adenocarcinoma embedded in prominent, cytologically uniform spindle cells. These cells were histologically distinct from the carcinoma; there were no zones of transition. The carcinoma was strongly positive for cytokeratin but only weakly positive for vimentin; the spindle cells expressed vimentin but not cytokeratin. We diagnosed this lesion as carcinoma with a reactive spindle cell stroma. A fifth mural nodule was composed entirely of interlacing fascicles of uniform spindle cells that were negative for cytokeratin but positive for vimentin, muscle-specific actin, and desmin; these findings support a diagnosis of leiomyoma. Two of the four patients with malignant nodules died of disease; the rest are alive and disease-free after follow-up intervals ranging from 1 to 4 years. This study demonstrates the usefulness of immunohistochemistry in distinguishing variant forms of spindle cell mural nodules in cystic ovarian mucinous tumors. It further suggests that malignant nodules do not necessarily carry a poor prognosis.

An immunohistochemical study of normal endometrial stroma and endometrial stromal neoplasms. Evidence for smooth muscle differentiation

To determine the immunohistochemical staining profile of endometrial stromal cells, we analyzed a series of formalin-fixed, paraffin-embedded normal endometrial tissues, stromal nodules, and stromal sarcomas for immunoreactivity with a panel of eight antibodies. Normal proliferative-phase (five cases) and secretory-phase (five cases) endometrial stromal cells showed the following immunopositivity: vimentin 10 of 10, muscle-specific actin (MSA) 10 of 10, alpha-smooth muscle actin (alpha sm) 10 of 10, desmin nine of 10, cytokeratin (AE1/AE3 and CAM 5.2) zero of 10, epithelial membrane antigen (EMA) zero of 10, and S-100 protein zero of 10. Antibodies to vimentin, MSA, and alpha sm stained a greater number of proliferative-phase stromal cells as compared with secretory-phase cells. Only rare stromal cells were immunoreactive for desmin, except for one case in which predecidual cells were diffusely positive. Both endometrial stromal nodules reacted with antibodies to MSA, alpha sm, and desmin, and one was vimentin positive. Each was unreactive for epithelial markers and S-100 protein. The 12 endometrial stromal sarcomas had the following immunopositivity: vimentin 11 of 12, MSA 10 of 12, alpha sm 10 of 12, desmin seven of 12, AE1/AE3 one of 12, CAM 5.2 two of 12, EMA zero of 12, and S-100 protein zero of 12. The antibodies to MSA and alpha sm usually stained a greater number of cells than did the desmin antibody. Three stromal sarcomas had sex cord-like areas, one of which exhibited focal CAM 5.2 positivity. These immunohistochemical findings for normal and neoplastic endometrial stromal cells indicate smooth muscle differentiation and are similar to those of smooth muscle neoplasms and myofibroblastic cells.

Immunoreactivity for estrogen receptor protein in sweat gland tumors

The histologic and immunophenotypic similarities between sweat gland carcinoma and breast cancer are well known. Indeed, these likenesses often preclude the diagnostic separation of primary cutaneous glandular neoplasms from metastatic mammary carcinomas, based on light microscopic and immunohistochemical features alone. To assess whether the presence of estrogen receptor protein (ERP) in breast carcinoma might serve as a diagnostic marker in this context, we analyzed 33 eccrine carcinomas, 24 sebaceous carcinomas, 15 intraepidermal apocrine carcinomas (extramammary Paget's disease), and 42 benign sweat gland tumors for ERP content. The monoclonal anti-ERP H222 was used with a modified avidin-biotin-peroxidase complex (ABC) method and paraffin sections. For comparison, eight cutaneous metastases of mammary carcinomas were similarly studied. ERP was identified in six of eight secondary neoplasms. However, this steroid-binding protein also was detected in 10 of 33 eccrine carcinomas. In three of 10 eccrine hidradenomas, each of two examples of hidradenoma papilliferum, and two of three chondroid syringomas, ERP-reactivity was noted as well. The remaining eccrine, apocrine, and sebaceous neoplasms were nonreactive. Among immunoreactive eccrine neoplasms, eight of 10 carcinomas occurred in males, whereas most ERP-positive benign eccrine tumors arose in females. The potential expression of ERP by sudoriferous malignancies reinforces the biologic similarities between mammary and cutaneous adnexal neoplasms. Moreover, ERP reactivity in the latter lesions underscores the inability of immunohistochemistry to distinguish primary and secondary glandular tumors of the skin with certainty.

Injury to the pre-pubertal vas deferens. II. Experimental repair

We have previously shown that the human vas deferens does not change in cross-sectional size between birth and the middle of puberty. This suggests that if the human vas is injured prior to mid-puberty, repair by a traditional microsurgical vasovasostomy may be technically difficult. We propose that a chromic stent can be used to assist in the repair of vas injured before mid-puberty. This hypothesis was tested in Sprague-Dawley rats. At three weeks of age, male offspring were divided into three groups (eight to nine rats/group): 1) Sham group--a sham operation at three weeks, 2) VV group--bilateral transection of vasa at three weeks followed by a delayed repair at eight weeks by microsurgical vasovasostomy without a stent, 3) Stent group--bilateral transection of vasa at three weeks followed by immediate repair by aligning the lumens with a 6-0 chromic intravasal stent (suture) and holding the transected ends together with several seromuscular sutures. At four months all rats were fertility tested and a score was given to each rat (mean number of concepti among three females for each male rat). Analysis of anastomotic patency by flow rates and histology was performed. There was no statistical difference in the mean fertility score of 6.85 in the Stent group compared to 7.83 in the Sham group. However, a fertility score of 0.71 in the VV group was significantly decreased compared to the Stent and Sham group (p = .0003), despite no statistical difference between the groups in patency. This suggests that a recognized injury to the pre-pubertal human vas should be immediately repaired and the repair can be done using 6-0 chromic suture as an intravasal stent to help align the lumina of the smaller pre-pubertal vas.

Injury to the pre-pubertal vas deferens. I. Histological analysis of pre-pubertal human vas

There is very little information in the literature on the development of the human vas deferens. Therefore, the age at which the pre- or para-pubertal vas deferens becomes large enough for a vasovasostomy to be technically feasible is unknown. To determine the age or degree of sexual maturity at which a microscopic vasovasostomy is technically feasible, we collected surgical or autopsy vasa from 34 young males over a three year period, and correlated vasal size to age and Tanner stage (degree of sexual maturity ranging from 1-childhood to 5-adult). The specimens were embedded and sectioned transversely in glycol methacrylate. Using image analysis, the total transverse area and diameter, and luminal area and diameter was determined for each specimen. Surprisingly, there was no change in vasal size from birth up through 11 years. From age 15 years and on, the vas was adult in size. The vas develops to adult size between Tanner stages 2 and 3. The average external and luminal diameters of pre-midpuberty specimens (Tanner stages 1 and 2) were 1.0 and 0.19 (mm.) and the diameters of post-midpuberty specimens were 2.1 and 0.43 (mm.), respectively. These results suggest that, in the event of a recognized iatrogenic injury to the vas deferens after midpuberty, a repair by a traditional microsurgical vasovasostomy is possible. If the vas is injured before midpuberty it may be technically difficult to repair by traditional microsurgical methods.

Clear cell tumor of the lung. Immunohistochemical and ultrastructural evidence of melanogenesis

Clear cell tumors of the lung (CCTL) are rare neoplasms of uncertain differentiation. A previous study of eight CCTL demonstrated a lack of epithelial features, but their exact nature remained unknown. In the current study of nine CCTL, immunohistochemistry using preliminary enzymatic digestion showed strong reactivity with the antimelanocytic markers HMB-45 (seven cases) and HMB-50 (six cases) and focal positivity for S-100 (nine cases), neuron-specific enolase (three cases), synaptophysin (one case), and Leu-7 (one case). Staining for cytokeratin, epithelial membrane antigen, chromogranin, and glial fibrillary acid protein was uniformly negative. Frozen-section immunoreactivity for vimentin and the antimelanocytic monoclonal preparation NKI/BETEB was noted in the one CCTL for which snap-frozen tissue was available. Ultrastructural examination of three glutaraldehyde-fixed CCTL showed rare neoplastic cells containing the full spectrum of melanosomes in two, one of which also contained neurosecretory-type granules. Aberrant melanosomal forms were identified in the third case. Melanosomes were not identified in the remaining five CCTL studied from formalin- or paraffin-retrieved material. The findings indicate that CCTL exhibits melanocytic differentiation. This feature may be of considerable value in distinguishing CCTL from other clear cell neoplasms.

Histologic classification of sinonasal intestinal-type adenocarcinoma

Kleinsasser and Schroeder recently described a histologic classification system for woodworker-associated, intestinal-type adenocarcinomas of the sinonasal region. To determine if their approach is easily applied and prognostically meaningful for both woodworker-associated and sporadic intestinal-type adenocarcinomas in the sinonasal region, we analyzed 15 such cases. The 12 men and three women ranged in age from 37 to 75 years. Only four were woodworkers. All tumors arose in the nasal cavity or paranasal sinuses. The three authors independently classified the tumors with unanimous agreement in 11 (73%) of 15 cases. Disagreements were resolved by group review and consensus. Ten tumors were papillary tubular cylinder cell type; these were subdivided into grades I (four cases) and II (six cases) on the basis of cytologic atypia. Three tumors were alveolar goblet cell type; one tumor was signet-ring type; and one had a mixed pattern. Median survivals were papillary tubular I, 9 years; papillary tubular II, 3 years; and alveolar goblet cell, 7 years. It is concluded that this classification system is easy to apply, reproducible, and appears to identify a group of sinonasal intestinal-type adenocarcinomas (papillary tubular I) with a prolonged survival.

Malignant peritoneal mesothelioma in childhood with long-term survival

A diffuse, well-differentiated, malignant peritoneal mesothelioma (MPM) developed in a nine-year-old girl. She received limited chemotherapy and radiation therapy and is alive and well without clinical evidence of disease 109 months after diagnosis. The neoplastic cells stained immunohistochemically for cytokeratin and epithelial membrane antigen but were unreactive with B72.3, anti-carcinoembryonic antigen, and anti-Leu-M1. Ultrastructurally, the tumor cells had abundant desmosomes, numerous tonofilament bundles, and variable-length microvilli. These findings confirm the mesothelial nature of the cells. Features consistent with malignancy included DNA aneuploidy by flow cytometric analysis and diffuse peritoneal involvement. The three previously described survivors with MPM were also premenarchal girls. Some MPMs in premenarchal girls have an indolent biologic behavior similar to that of low-grade peritoneal serous neoplasia or well-differentiated papillary mesothelioma in adult women.

Uterine intravascular menstrual endometrium simulating malignancy

Intravascular menstrual endometrium, a rare finding in hysterectomy specimens, can pose clinically critical differential diagnostic problems. We describe a 28-year-old female with cervical dysplasia and numerous foci of menstrual endometrium in the parametrial blood vessels of her subsequent hysterectomy specimen. Histologically, the intravascular tissue consisted of small spindled stromal cells, larger cuboidal epithelial cells, or both components in close association. Immunohistochemically, the small spindled cells were vimentin positive and the larger cuboidal cells stained with epithelial markers. Distinction of intravascular menstrual endometrium from intravascular malignancies such as carcinoma, sarcoma, or lymphoma may be difficult, especially at the time of frozen-section diagnosis. Awareness of this process, attention to its cytologically bland, usually biphasic appearance, knowledge of the menstrual status, and application of appropriate immunohistochemical markers will allow distinction from neoplasia.

Interaction of somatotropin and genotype on the requirement for energy in two lines of finishing pigs

Eighty barrows were used in a 2 x 2 x 4 factorial experiment to examine the effects of genetic line (Hampshire x Yorkshire, H x Y, and Yorkshire x Landrace, Y x L), somatotropin (dose, 0 and 5 mg/d) and energy intake (ad libitum, 93%, 86% and 80%) on growth performance and energy requirements for lean gain over the finishing phase of growth. Four diets were formulated to maintain equal intakes of protein, vitamins and minerals at different energy intakes. Somatotropin increased growth rate 30 to 35% across diets despite an 8 to 12% reduction in ad libitum feed intake. Lean growth rate (kg/d) was increased preferentially by ST in the faster-growing H x Y barrows, which showed a 2.8-fold greater maximum rate increase than the slower-growing Y x L barrows. In control barrows, 10% reductions in energy intake had no effect on lean gain and improved feed/lean gain about 10%. In somatotropin-treated barrows, lean gain was reduced with each energy restriction in H x Y; energy intake had no effect on lean gain in Y x L barrows. Feed/lean gain was improved 22% in Y x L barrows at the lowest energy intake. Data indicate that somatotropin accentuates breed differences in lean gain and energy requirements. Pigs with low lean-growth potential will benefit from restricted feeding, whereas strategies to increase energy intake in pigs with high lean-growth potential may be desirable.

Small-cell neuroendocrine carcinoma of the cervix. A human papillomavirus type 18-associated cancer

Small-cell undifferentiated carcinomas comprise a rare but aggressive subset of uterine cervical neoplasms. Analogous to small-cell anaplastic carcinoma of the lung, these tumors frequently exhibit neuroendocrine differentiation. Although human papillomaviruses (HPV) types 16 and 18 are strongly associated with the development of cervical squamous carcinoma, there is as yet little information describing the relationship of these viruses to small-cell carcinomas. To address this question, we analyzed 20 cases of small-cell carcinoma of the cervix using in situ hybridization to detect HPV gene expression. In addition, immunohistochemistry was used to evaluate three markers of neuroendocrine differentiation. Eighteen of 20 tumors (90%) demonstrated some evidence of neuroendocrine differentiation; 17 of 20 (85%) expressed HPV type 16 or 18 messenger RNA. Of the neuroendocrine-positive cases, 14 of 18 expressed HPV 18 messenger RNA. In contrast, both of the cases with squamous differentiation were HPV 16 positive. These findings broaden the spectrum of HPV-associated cervical neoplasia and strongly suggest that HPV 18 is a viral type specifically associated with cervical small-cell neuroendocrine carcinomas.

Unusual variants of adrenal pseudocysts with intracystic fat, myelolipomatous metaplasia, and metastatic carcinoma

Five previously unreported cases of adrenal pseudocysts are described that demonstrate a wider range of histologic appearances than has been previously recognized in these lesions. One pseudocyst removed from an asymptomatic 59-year-old female contained intracystic nests of cytologically malignant cells of unknown origin. Workup revealed a left breast mass, which on biopsy showed an infiltrating ductal carcinoma with neoplastic cells that were cytologically similar to those found within the cyst contents. Four other pseudocysts are described with variable numbers of intracystic vascular structures and benign adrenal cortical cells. In addition, intracystic mature adipose tissue was observed in all four cases, with myelolipomatous metaplasia found in one. Awareness of the wide histologic variability of these lesions should improve diagnostic accuracy and allow distinction from adrenocortical neoplasia and myelolipoma.

Thymomas and thymic carcinomas

This review discusses epithelial proliferations of the thymus, excluding carcinoid tumor and small cell carcinoma. The clinical features of thymoma, possible etiologic mechanisms, and associated autoimmune and paraneoplastic conditions are summarized briefly. Histologic subtypes of thymoma, including lymphocyte predominant, mixed, and spindle cell tumors are described and illustrated. The concept of "medullary" and "cortical" differentiation in thymoma is reviewed. Immunohistochemical and electron microscopic features of this neoplasm are presented. Flow cytometric studies relating to its prognosis also are summarized. Distinctions between encapsulated thymoma, invasive thymoma, and metastatic or "malignant" thymoma are described in detail. Thymic carcinomas are reviewed, as distinguished from cytologically bland thymomas. Variants of thymic carcinoma include squamous cell, spindle cell, lymphoepithelioma-like, mucoepidermoid, adenosquamous, clear cell, basaloid, and adenoid cystic neoplasms.

Olfactory neuroblastoma. Additional immunohistochemical characterization

A panel of 12 antibodies was used to further characterize the immunohistochemical staining profile of olfactory neuroblastoma. The following results were obtained for the 11 neoplasms that were immunostained: neuron-specific enolase 11/11(+), S-100 protein 8/11(+), microtubule-associated protein-2 8/11(+), class III beta-tubulin isotype 9/11(+), neurofilament 200 kD 8/11(+), synaptophysin 7/11(+), glial fibrillary acidic protein 1/11(+), chromogranin A 1/11(+), vimentin 1/11(+), keratin (CAM 5.2) 4/11(+), keratin (AEI/AE3) 0/11(+), and epithelial membrane antigen 0/11(+). Expression of two intermediate filaments was found in 4 of the 11 tumors. The authors' data showing that 72% of olfactory neuroblastomas were S-100 protein positive and only one was immunoreactive for glial fibrillary acidic protein agree with other published immunohistochemical studies. With only a single exception, each of the 11 neoplasms was labeled with one or more antibodies that detect neuronal cytoskeletal proteins (class III beta-tubulin isotype, microtubule-associated protein-2, neurofilament 200 kD). These immunohistochemical results are complementary to the reported electron microscopic findings of intermediate filaments and microtubules in olfactory neuroblastomas.

Neuroendocrine carcinoma of the colon and rectum. A clinicopathologic, ultrastructural, and immunohistochemical study of 24 cases

To further characterize the clinicopathologic spectrum of colorectal neuroendocrine neoplasia, 24 carcinomas with neuroendocrine differentiation were subtyped as either small cell neuroendocrine, oat cell variant (six cases), small cell neuroendocrine, intermediate variant (16 cases), or moderately differentiated neuroendocrine carcinoma (two cases). Five oat cell variants, 14 intermediate variants, and two moderately differentiated tumors were studied with antibodies to cytokeratin, vimentin, epithelial membrane antigen (EMA), neuron-specific enolase (NSE), chromogranin (CRG), synaptophysin (SYN), neurofilament, S-100 protein, carcinoembryonic antigen (CEA), and Leu-7. All tumors were immunoreactive for cytokeratin and the majority were also positive for EMA and NSE. Positivity for specific neuroendocrine markers was uncommon, with SYN reactivity noted in one oat cell variant and four intermediate variants, and CRG positivity observed in four intermediate variants and one moderately differentiated tumor. Ultrastructural analysis of four oat cell, eight intermediate, and one moderately differentiated tumor revealed neurosecretory-type, dense-core granules in all lesions, except two oat cell variants studied from paraffin-retrieved material. Hepatic and regional lymph node metastases were noted in five of six oat cell, eight of 16 intermediate, and two of two moderately differentiated tumors. Of 17 patients with follow-up (four oat cell, 11 intermediate, and two moderately differentiated tumors), only two individuals were alive after 1 year. There were no detectable differences in survival or response to treatment between morphologic subtypes. The prognosis of colorectal neuroendocrine carcinoma appears worse than for adenocarcinoma of comparable stage. Their distinction is thus warranted, especially in regard to the intermediate variant and moderately differentiated tumors, which may be potentially misinterpreted as forms of adenocarcinoma.

Oocyte retention after follicle luteinization

Indirect evidence supports the existence of the luteinized unruptured follicle syndrome in infertile women. To seek direct evidence of oocyte retention, infertile and normal women were studied in the early and midluteal phase by visual documentation of ovulation stigma, needle aspiration of ovarian follicles, and peritoneal fluid collection for estradiol and progesterone assay. Luteal phase was confirmed by endometrial biopsy (postovulation day 2 to 8). In normal control subjects (n = 16), 25% of test cycles were stigma-negative and no oocytes were recovered. In infertile group (n = 23), 43% of test cycles were stigma-negative. Five oocytes were recovered including one from a stigma-bearing follicle. Peritoneal fluid steroid levels failed to discriminate stigma-positive from stigma-negative cycles in either group. Oocyte retention after luteinization occurs in infertile women.

Use of brefeldin A to define sites of glycosphingolipid synthesis: GA2/GM2/GD2 synthase is trans to the brefeldin A block

Brefeldin A (BFA) induces the rapid redistribution of the Golgi complex into the endoplasmic reticulum (ER), causing the glycoproteins that are retained in the ER to be processed by Golgi enzymes. We have examined the effects of BFA on the synthesis of glycosphingolipids (GSL) to map the intracellular sites of GSL synthesis. In several cultured cell types, BFA inhibited the synthesis of the neutral GSL gangliotriaosylceramide (GA2) and monosialoganglioside GM2 and disialoganglioside GD2, where GD2 is GalNAc(beta 1----4)- [NeuAc(alpha 2----8)NeuAc(alpha 2----3)]Gal(beta 1----4)GlcCer, GM2 lacks the NeuAc(alpha 2----8) unit, and GA2 lacks both NeuAc(alpha 2----8) and NeuAc(alpha 2----3) units. The observed decrease in labeling of GA2, GM2, and GD2 in the presence of BFA was not due either to enhanced degradation of these glycolipids or to shedding of these glycolipids from the cells. In rat liver all three of these glycolipids have been shown by others to be synthesized by the same enzyme, GA2/GM2/GD2 synthase, which catalyzes the addition of N-acetylgalactosamine to lactosylceramide (Lac-Cer), GM3 [NeuAc(alpha 2----3)Gal(beta 1----4)GlcCer], and GD3 [NeuAc(alpha 2----8)NeuAc-(alpha 2----3)Gal(beta 1----4)GlcCer], respectively. Studies with a fluorescent glycolipid analog indicated that BFA redistributed the trans-Golgi stacks into a reticular pattern characteristic of the ER. These studies localize GA2/GM2/GD2 synthase, a key enzyme involved in the synthesis of complex gangliosides, to a compartment late in the intracellular trafficking pathway, which remains functionally distinct from the ER in the presence of BFA.

Expression of "myelomonocytic" antigens in mesotheliomas and adenocarcinomas involving the serosal surfaces

Because of the demonstrated efficacy of Leu-M1 as a discriminant between malignant epithelioid mesothelioma (MEM) and adenocarcinomas involving the serosal surfaces (ACSs), the authors assessed the reactivities of related "myelomonocytic" antigens in this context. Paraffin sections from 41 MEMs and 43 ACSs (pulmonary, "serous surface papillary," and metastatic mammary adenocarcinomas) were evaluated for their expression of Leu-M1, LN1, LN2, and the Mac 387 antigen. Diagnoses were based in each case on the results of conventional histologic and electron microscopic examinations. Leu-M1 was detected only in minute foci of three peritoneal MEMs and was absent entirely in pleural mesotheliomas. Conversely, 38 of 43 ACSs expressed this marker. Three cases of peritoneal MEM and one pleural mesothelioma were multifocally LN2 positive, as were 39 of 43 ACSs. LN1 was the most frequently expressed antigen in MEM, being observed in 18 such tumors (10 pleural; 8 peritoneal); it was also detected in 37 of 43 ACSs. Mac 387 failed to label any of the neoplasms assessed in this series. These results demonstrate similar patterns of "myelomonocytic" antigen expression by diverse ACS and a general absence of Leu-M1 and LN2 in MEM. LN1 and the Mac 387 antigen appear to have no additional value when compared with Leu-M1 and LN2 in the immunohistochemical evaluation of serosal neoplasms.

Malignant epithelioid pleural mesothelioma versus peripheral pulmonary adenocarcinoma: a histochemical, ultrastructural, and immunohistologic study of 103 cases

The distinction between malignant epithelioid pleural mesothelioma (MEPM) and peripheral adenocarcinoma of the lung with pleural invasion (PAL) continues to represent a diagnostic challenge in selected cases. In order to provide comparative data on histologic, histochemical, and immunohistochemical features of these neoplasms, we analyzed 51 ultrastructurally categorized MEPMs and 52 PALs with the periodic acid-Schiff-diastase (PAS-D), mucicarmine, and colloidal iron stains, and a panel of immunohistologic reagents. Antibodies to cytokeratin, vimentin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), Leu M1, the B72.3 antigen, blood group isoantigens (BGI), placental alkaline phosphatase, amylase, S100 protein, and Clara cell antigen were used, as applied to paraffin sections with the avidin-biotin-peroxidase complex technique. Ultrastructural studies revealed long, branching microvilli in MEPM cells in all cases, with length-to-diameter ratios (LDR) of 10:1 or more. In contrast, PAL manifested short, nonbranching microvilli with LDR of 8:1 or less. Reactivity with PAS-D and mucicarmine stains was strictly confined to PAL, and hyaluronidase-sensitive colloidal iron-positivity was restricted to MEPM. However, only 63% and 41% of these respective neoplasms demonstrated such histochemical reactivity. Immunohistologic results correlated well with electron microscopic classification. All MEPMs and PALs were reactive for cytokeratin; in addition, the majority of tumors in each group expressed EMA, and a minority were reactive for vimentin. In adenocarcinomas of the lung, Leu M1 was observed in all cases, CEA was apparent in 96%, B72.3 labeled 84%, and BGI were present in 67%; all PALs expressed at least two of these determinants, but none was seen in any mesothelioma. The other markers included in this study also were observed in some PAL cases, but not in MEPM. These findings suggest that immunohistology parallels electron microscopy in efficacy in the diagnostic separation of MEPM and PAL. Using antibodies to Leu M1, CEA, and the B72.3 antigen, reactivity for at least two of these three markers appears to exclude a diagnosis of pleural mesothelioma. The other glycoproteinaceous, oncoplacentofetal, and cytoplasmic antigens we studied can be used to reinforce such a determination, since their distribution is confined to adenocarcinomas.

Histiocytoid (epithelioid) hemangioma of the testis. The so-called vascular variant of "adenomatoid tumor"

Adenomatoid tumors are well-recognized neoplasms generally considered to be of mesothelial derivation. We describe an unusual vascular neoplasm that arose in the testis of a 29-year-old and resembled an adenomatoid tumor by light microscopy. An orchiectomy was performed, and the patient is alive and disease-free 3 years later. The 2-cm tumor was composed of small tubules lined by mesothelial-like cells with uniform, vesicular nuclei. However, some lumina contained erythrocytes, and immunohistochemically, the luminal cells reacted with antibodies to vimentin, Factor VIII-related antigen, and Ulex europaeus I lectin but not cytokeratin or epithelial membrane antigen. A cuff of muscle-specific actin-positive cells surrounded the luminal cell layer. This adenomatoid-like vascular neoplasm is more properly interpreted as a histiocytoid (epithelioid) hemangioma. Although some authors have considered microscopically similar lesions to represent a vascular variant of adenomatoid tumor, we prefer to reserve the term "adenomatoid tumor" for microscopically appropriate proliferations that have mesothelial features.