Abundant Mucin Research Articles

Fine‐needle aspiration cytology of intraductal papillary‐mucinous tumors: A retrospective analysis

Intraductal papillary-mucinous tumor (IPMT) of the pancreas has become the accepted terminology for a group of mucin-producing epithelial proliferations lying within ectatic segments of the main pancreatic duct or its large branches. These neoplasms generally are associated with an indolent course, characteristic endoscopic ultrasonographic (EUS) findings, and a variable histo- and cytomorphology ranging from hyperplasia to carcinoma. Cytological specimens obtained by endoscopic ultrasound-guided or percutaneous fine-needle aspiration (FNA) are characterized by a background containing abundant mucin in which are entrapped single or loosely cohesive clusters of neoplastic cells characteristically showing a goblet-cell morphology. The degree of nuclear atypia, cell crowding, and cell shape varies between smears within a single case and between cases. Cytomorphological examination, when coupled with EUS features, is accurate for the diagnosis of these lesions but often it underdiagnoses the grade of the neoplasm.

Well-differentiated adenocarcinoma of the gallbladder with intratumoral cystic components due to abundant mucin production: a mimicker of adenomyomatosis

The prevalence and etiology of the cystic components within gallbladder carcinomas as seen on MR images were evaluated. A retrospective review of MR images was performed for 35 proven gallbladder carcinomas in search of radiologically detectable intratumoral cystic components. The pathologic specimens were meticulously reviewed to determine the etiology. MR images of 31 adenomyomatoses were also reviewed for comparison to clarify the difference in MR features between these two entities. Three cases out of 35 proven gallbladder carcinomas were found to have intratumoral cystic components. They were all well-differentiated adenocarcinomas, and the cystic components consisted of dilated neoplastic glands filled with abundant mucin pool. Adenomyomatosis tended to have more and rounded cystic components (Rokitansky-Aschoff sinuses) lined in a linear fashion and were flat-elevated in shape, smaller in size and had a regular surface, as compared to the three carcinomas. Although rare, radiologists need to be aware that well-differentiated gallbladder carcinoma with mucin production can have cystic components, which may mimic adenomyomatosis. Careful interpretation of MR images may provide useful information in the differentiation of these two entities.

Clinicopathologic characteristics of early-stage mucinous gastric carcinoma.

Early mucinous gastric carcinoma (MGC) is very rare, and the clinicopathologic features are not well understood. The aim of this study is to clarify the clinicopathologic characteristics of early MGC. A total of 806 patients with gastric cancer underwent gastrectomy between 1983 and 2002 at our department. Of these patients, 7 were found to have early MGC. MGC was defined as a tumor in which more than 50% of the tumor area contained extracellular mucin pools. Microscopic examination was performed, and particular attention was paid to the mucin component of the tumor and histologic subtype (ie, well-differentiated or poorly-differentiated). The incidence of early MGC among all gastric carcinomas in our series was 0.9% (7/806). Tumors ranged in size from 1.0 cm to 7.2 cm, with a mean of 3.7 cm, and 4 appeared macroscopically elevated and 3 appeared depressed. Histologically, 3 tumors were considered well-differentiated type and 4 were considered poorly differentiated type. Microscopic features were thickening of the submucosal layer due to accumulation of abundant mucin and elevation of the surrounding normal mucosa. Tumor invaded the submucosa in 6 cases, and lymph node metastasis occurred in 1 case. However, no patient died of recurrence during follow-up periods ranging from 4 to 85 months. Early MGC is characterized as an elevated lesion resembling submucosal tumor due to abundant mucin pools in the submucosa. Cases of early MGC have a good outcome similar to that of early non-MGC.

Pathologically and biologically distinct types of epithelium in intraductal papillary mucinous neoplasms: delineation of an "intestinal" pathway of carcinogenesis in the pancreas.

Although general characteristics of intraductal papillary mucinous neoplasms (IPMNs) and their delineation from other pancreatic tumors have been well established, several issues regarding their biology and management remain unresolved. It has been noted briefly by us and other authors that there are different types of papillae in IPMNs; however, their frequency, biologic significance, and clinical relevance are unknown. In this study, the association of different papillary patterns with clinical, pathologic, and biologic parameters was studied in 74 IPMNs, and the expression profile of CDX2 (a specific marker and one of the key determinants of intestinal "programming," and a tumor suppressor) was determined immunohistochemically in addition to MUC1 (a marker of an "aggressive" phenotype in pancreatic neoplasia) and MUC2 ("intestinal type mucin," a marker of the "indolent" phenotype, and a tumor suppressor). The patterns of papillae identified and their association with these parameters were as follows: 1) The intestinal-type (Yonezawa's dark-cell type), similar to villous adenomas, was seen in 26 of 74 (35%) cases. The majority harbored carcinoma in situ (85%) or borderline atypia (15%). They tended to be large (mean, 5.5 cm). Most expressed CDX2 (95%) and MUC2 (92%) but not MUC1 (8%). This type was more commonly associated with colloid-type invasion (14 of 16 invasive carcinomas were of colloid type). 2) The pancreatobiliary type, characterized by arborizing papillae lined by cuboidal cells resembling papillary neoplasms of the biliary tract, was present in 22% of the cases. These were mostly graded as carcinoma in situ (94%); they rarely expressed CDX2 (6%) or MUC2 (19%) but often showed MUC1 labeling (44%). This pattern was more commonly associated with the tubular type of invasive carcinoma and had a slight tendency for a more aggressive clinical course. 3) The null type was characterized by abundant apical mucin and basally located nuclei, similar to the gastric foveolar epithelium. Thirty-one percent of IPMNs had this type of papillae, but this pattern was also present in the background of other IPMNs and in the cystic components of most cases as well. Most pure null-type IPMNs were devoid of complexity and consequently classified as adenoma (48%). They tended to be small (mean, 2.6 cm), were often negative for CDX2, MUC1, and MUC2, and were rarely associated with invasive carcinoma. 4) Some IPMNs (12%) exhibited features that were difficult to classify, and 2 cases had a mixture of pancreatobiliary and intestinal types of papillae. In conclusion, IPMNs include pathologically and biologically distinct epithelial patterns. CDX2 and MUC2 expression is relatively specific for the intestinal type papillae, confirming that these IPMNs indeed exhibit intestinal differentiation. Their close association with colloid carcinoma, which also shows consistent MUC2 and CDX2 expression, supports the existence of an intestinal pathway of carcinogenesis. This "metaplastic" pathway may reflect different genetic events in the development of these IPMNs, and the presence of intestinal differentiation may potentially be used in prognostication and stratification of patients into appropriate treatment categories.

Pseudomixoma peritoneal tipo adenomucinosis peritoneal diseminada con imágenes radiológicas atípicas

Pseudomyxoma peritonei is an unusual condition that has caused much confusion regarding its aetiology, clinical manifestations, treatment and prognosis. It is characterised by mucinous ascites and diffuse mucinous invasions of the peritoneum. Three histological subtypes have been defined: a) disseminated peritoneal adenomucinosis (peritoneal lesions composed of abundant extra-cellular mucin containing scant simple-to-focally-proliferating mucinous epithelium with little cytological atypia or mitotic activity); b) peritoneal mucinous carcinomatosis (peritoneal lesions composed of more abundant mucinous epithelium with the architectural and cytological features of carcinoma); and c) an intermediate group. The different histological subtypes have different prognoses.

Fine-needle aspiration cytology of mucinous tumors of the pancreas.

Tumors of the pancreas associated with extracellular mucin production include mucin-producing ductal adenocarcinoma, mucinous cystic neoplasm (MCN), and intraductal papillary mucinous tumor (IPMT). Fine-needle aspiration (FNA) is used as an adjunct to radiologic analysis for the preoperative categorization of these tumors. The current study was designed to identify distinctive cytomorphologic features that would be useful for the categorization of mucinous tumors of the pancreas. The authors evaluated Papanicolaou smears and Diff-Quik-stained smears of specimens obtained by computed tomography-guided and endoscopic ultrasound-guided FNA of the pancreas in 51 cases of mucinous tumors. In the 19 cases in which the patients underwent surgical excision after FNA, the cytologic features were compared with the histopathologic findings. The remaining cases were categorized as one of the three above-mentioned types of mucinous tumors on the basis of cytomorphologic features identified as indicative of subtype among the cases in which a cytologic-histologic correlation was performed. Among the 19 cases with cytologic-histologic correlation, 2 cases of serous cystadenoma and 2 cases of gastrointestinal duplication cyst were misdiagnosed on cytologic analysis as low-grade MCN. Among the remaining 15 cases, cytologic features by histologic diagnosis were as follows: ductal adenocarcinoma (n = 4): moderate to high cellularity, mild to moderate background mucin, three-dimensional clusters, high nuclear cytoplasmic ratios, and mild to moderate nuclear membrane irregularities; low-grade MCN (n = 5): mild to moderate cellularity, abundant background mucin, small clusters, and flat sheets of relatively bland glandular cells; mucinous cystadenocarcinoma (n = 1): similar to ductal adenocarcinoma but more abundant background mucin; and IPMT (n = 5): moderate to high cellularity, abundant background mucin, and prominent papillary arrangement of tall columnar cells with mild to moderate nuclear atypia. The remaining 32 cases were categorized based on cytology alone as adenocarcinoma with mucin production (n = 24) and low-grade MCN (n = 8). IPMT and low-grade MCN possess distinctive cytologic features that can be used to diagnose them correctly and distinguish them from one another and from other cystic tumors. Duplication cysts closely mimic low-grade MCN, which can lead to false-positive diagnoses. Because of substantial overlap in cytologic features, mucin-producing ductal adenocarcinoma was unable to be distinguished from mucinous cystadenocarcinoma cytologically.

A Case of Primary Signet Ring Cell Carcinoma of Lung with Multiple Bone Metastasis

Signet ring cell carcinoma of lung is an unique variant of mucin producing adenocarcinoma which is characterized by abundant intracellular mucin accumulation. Only a few cases of primary signet ring cell carcinoma of lung have been reported in the world wide literature. And we have, recent ly experienced one case of primary signet ring cell carcinoma of lung. A 55 years old man was evaluated for paralysis of lower extremities and was found to have lung cancer in the left upper and lower lobe with pleural, multiple spinal, bone and liver metastases. Signet ring tumor cells were revealed by cytologic examination of pleural fluids. And there were no evidence of signet ring cell carcinoma of other organs. Primary signet ring cell carcinoma of lung seems to have an aggressive behavior and therapeutic modalities could be different from those for signet ring cell carcinomas from other organs. Therefore it is important to separate primary signet ring cell adenocarcinoma of lung from metastatic tumors. (Tuberc Respir Dis 2004; 57:594-598)

子宮体部粘液性腺癌の１例

The case of a 48-year-old woman with endometiral mucinous adenocarcinoma is reported. Endometrial cytology findings papillary and palisade shaped tumor cell clusters resembling those of endcervical adenocarcinoma. The tumor cells contained abundant intracellular and extracellular mucin. The endometrialmucinous adenocarcinoma cells were distinguished from endocervical adenocarcinoma cells both pathologically and histochemically.

Atypical Cellular Neurothekeoma

BACKGROUND Neurothekeoma is a distinctive neoplasm that in the past was often lumped into the broad category of benign peripheral nerve sheath tumors. Atypical cellular neurothekeoma is a rare variant of this neoplasm. This atypical variant is characterized by features that can include the following: large sizes (up to 6 cm), deep penetration extending into skeletal muscle and/or subcutaneous fat, diffusely infiltrative borders, vascular invasion, high mitotic rate, and marked cytologic pleomorphism. METHODS In this report, we describe the clinical, histopathologic, and immunohistochemical features of a case of atypical cellular neurothekeoma in a 34-year-old woman. RESULTS This neoplasm demonstrated both the cellular subtype and intermediate subtype. In the cellular area, cells demonstrated rounded or ovoid nucleus with abundant cytoplasm. Mitotic activity ranged from 8 to 12 per 10 high-powered fields, and few individual cell necroses were present. In the intermediate area, cells were arranged as smaller nests with admixed abundant mucin. Mitotic activity ranged from 1 to 2 per 10 high-powered fields. These cells were negative for S100, epithelial membrane antigen, and smooth muscle actin. CONCLUSION Dermatologists should be aware of the features of atypical cellular neurothekeoma. Although the atypical features raise concern about the malignant potential of this lesion, previous cases show that complete surgical excision of these lesions is curative.

Cloning and characterisation of the UDP-glucose 4'-epimerase of Trypanosoma cruzi.

Trypanosoma cruzi incorporates galactose into many of its cell-surface glycoconjugates but it is unable to transport this sugar through its hexose transporter. Epimerisation of UDP-glucose to UDP-galactose by UDP-glucose 4'-epimerase may be the only way that the parasites can obtain galactose. Here, we describe cloning the T. cruzi UDP-Glc 4'-epimerase (TcGALE) gene and show that it is functional by complementing an Escherichia coli epimerase-deficient strain. The T. cruzi GALE gene encodes a 42.4 kDa protein and the recombinant protein expressed in E. coli is a homodimer in solution with a specific activity of 3.8 U mg(-1) and K(m) for UDP-Gal of 114 microM. Unlike the human epimerase, T. cruzi UDP-Glc 4'-epimerase is unable to inter-convert UDP-N-acetylglucosamine and UDP-N-acetylgalactosamine. This may explain why T. cruzi initiates O-glycosylation of its abundant GPI-anchored surface mucins via GlcNAcalpha1-O-Thr/Ser rather than the GalNAcalpha1-O-Thr/Ser linkage that is common for mucins from many other eukaryotes.

Ofuji's disease with follicular mucinosis and its differential diagnosis from alopecia mucinosa.

Ofuji's disease (OD) or eosinophilic pustular folliculitis and human immunodeficiency virus-associated eosinophilic folliculitis (HIV-EF) both show eosinophil-rich folliculocentric infiltrates, and it is not clear whether they are distinguishable pathologically. Follicular mucinosis (FM) has been observed in lesions of EF; such cases need to be differentiated from alopecia mucinosa (AM). We compared various pathologic features in 13 cases of OD, 10 cases of non-OD-typed papular EF (seven HIV-positive and three HIV-negative), and five cases of AM. All cases of EF showed eosinophilic infiltrates affecting mainly the isthmus or/and sebaceous gland. Eosinophil-rich pilosebaceous pustules or/and microabscesses were noted in 69% of the biopsy specimens of OD, 73% of papular EF, 71% of HIV-EF, and 0% of AM. Mucin deposits, often abundant, were found in sebaceous lobules or/and isthmus in 41% of OD and 100% of AM. Compared with AM, OD with FM tended to show more numerous eosinophils, less abundant mucin, and most significantly, eosinophilic infundibular pustule or sebaceous microabscess. Our study suggests that OD and HIV-EF are indistinguishable pathologically and the diagnosis requires clinical correlation. FM was not uncommonly seen in lesions of OD. OD with FM may be difficult to differentiate from FM, especially in cases presenting with non-annular or non-pustular lesions, but the diagnosis might be facilitated by finding eosinophil-rich pustule, microabscess, or infiltrate in pilosebaceous units microscopically.

Diagnostic accuracy and pitfalls in fine-needle aspiration interpretation of Warthin tumor

Despite its well-defined histologic appearance, the often variegated cytomorphologic appearance of Warthin tumor (WT) on fine-needle aspiration (FNA) may lead to an erroneous cytopathologic interpretation. In this study, the authors analyzed the potential sources of diagnostic errors and overall accuracy of FNA diagnosis of WT. A retrospective search of The Johns Hopkins Hospital Surgical Pathology files (1985-2001) revealed 97 patients with WT, including 31 patients who underwent prior FNA. A comprehensive review of cytopathologic material was undertaken to calculate the overall accuracy of FNA and to identify sources of diagnostic error. All tumors presented in the parotid gland. Four tumors (13%) were deemed inadequate for interpretation due to insufficient material. The FNA diagnosis of WT was rendered in only 20 tumors (74%). The remaining 7 tumors (26%) were misdiagnosed on FNA as consistent with or suspicious for carcinoma or some other neoplastic process. A retrospective review of the tumors, which were over-called on FNA, showed a predominance of necrotic or cellular debris (n = 6 tumors; 22%), significant epithelial metaplasia with atypia (n = 4 tumors; 15%), background inflammation suspicious for tumor diathesis (n = 3 tumors; 11%), spindle cells (n = 1 tumor; 4%), and abundant mucin with keratinized squamous cells (n = 1 tumor; 4%). FNA is moderately accurate for diagnosing WT, with a 74% accuracy rate in the current series. Cytologic misinterpretation may occur due to a lack of characteristic cytomorphologic features of WT and overabundance of one or more of the following: squamous metaplasia/atypia, mucoid/mucinous background, spindle-shaped cells, and cystic/inflammatory debris. An adequate awareness of these potential sources of erroneous diagnoses, coupled with appropriate clinical findings, may result in a higher accuracy rate.

Low-Grade Tubular-Mucinous Renal Neoplasms: Morphologic, Immunohistochemical, and Genetic Features

The current classification system of renal tumors is based on morphologic criteria, as supported by genetic findings. We present a group of previously unclassified tumors with similar morphologic and genetic features, suggesting a new entity within renal neoplasms. Seven renal tumors from five patients (ages 31–67 years) were analyzed. All cases were stained with periodic acid–Schiff, Hale's colloidal iron (HCI), and Alcian blue (AB) at pH 2.5/1.0 with and without hyaluronidase (HA) digestion. Immunohistochemical (IHC) stains were performed for CK8, CK18, CK19, vimentin, villin, Tamm-Horsfall protein (THP), renal cell carcinoma marker (RCC), epithelial membrane antigen (EMA), ulex europaeus agglutinin (UEA-1), soy bean agglutinin (SBA), peanut agglutinin (PNA), and MIB-1. Comparative genomic hybridization (CGH) and loss of heterozygosity (LOH) studies were performed on all cases. All tumors showed circumscribed growth, a tubular growth pattern with focal solid areas, no significant nuclear atypia and absence of necrosis, desmoplasia, or inflammation. Abundant extracellular mucin was present. Immunohistochemistry stains support collecting duct origin (EMA+, PNA+, SBA±, CK 8/18/19+, vimentin±, UEA-1−, RCC−, villin−, THP−). The proliferative rate was low (<1%). CGH showed multiple consistent chromosomal losses (−1,-4, −6, −8, −9, −13, −14, −15, −22). Clinical outcome was favorable, with recurrences but no known distant metastases or death of disease. These findings are distinct from all previously classified renal neoplasms. Our data suggest the presence of a unique tumor entity within tumors of probable collecting duct origin: tubular-mucinous renal tumors of low malignant potential.

尿膜管癌の２例

We report 2 cases of urachal carcinoma having totally different cytological features. Tumor cells in case 1 were highly atypical. having scanty mucin in the cytoplasm and growing in papillary patterns. Tumor cells in case 2 showed mild atypia with abundant mucin. Case 1 was difficult to distinguish cytologically from poorly differentiated transitional cell carcinoma. Case 2 was difficult to distinguish from adenoma. A definitive diagnosis of urachal carcinoma having these cytological features can only be made combining characteristic clinical findings.

Almost all infiltrating colloid carcinomas of the pancreas and periampullary region arise from in situ papillary neoplasms: a study of 39 cases.

Colloid carcinomas of organs such as the breast, colon, and prostate have been well characterized. However, up until now there have been only a few studies of colloid carcinomas of the pancreas and periampullary region, and the number of colloid carcinomas in these studies has been limited. A search of our files revealed 39 resections for pancreatic and periampullary carcinomas with colloid differentiation. All neoplasms were extensively sampled. "Carcinomas with colloid differentiation" were defined as tumors associated with abundant extracellular mucin containing free-floating mucinous epithelial cells. Cases with >50% colloid differentiation were classified as "colloid carcinomas," whereas those with less were termed "carcinomas with focal colloid features." Cases with no colloid differentiation at all were designated "carcinomas without colloid differentiation." Of the 39 carcinomas, 31 were colloid carcinomas, and eight were carcinomas with focal colloid features. Twenty-seven were centered in the pancreas, seven were in the duodenum, and five were in the ampulla of Vater. Remarkably, 38 of the 39 carcinomas (97%) arose in association with an intraductal papillary mucinous neoplasm or a tubular/tubulovillous adenoma. Of the patients with colloid carcinomas, the 2-and 5-year actuarial survival rates were 69% and 29%, respectively. There was no significant difference in survival rates between patients with colloid carcinomas and patients with adenocarcinomas without colloid differentiation, whether or not the latter arose in association with intraductal papillary mucinous neoplasms or tubular/tubulovillous adenomas. In a multivariate model colloid differentiation was not an independent predictor of patient survival, while other factors such as tumor location, perineural invasion, vascular invasion, and margin status after resection independently influenced patient survival. Most colloid carcinomas of the pancreas and periampullary region arise in association with a well-defined in situ papillary neoplasm. The diagnosis of a pancreatic or periampullary colloid carcinoma should encourage the pathologist to search for an associated low-grade in situ component. In addition, colloid carcinomas of the pancreas and periampullary region do not necessarily have a better prognosis than carcinomas without colloid differentiation. Instead, other factors such as tumor location, perineural invasion, vascular invasion, and margin status after resection are far more important.

Differential expression of mucin genes in mammary and extramammary Paget's disease.

Paget's disease (PD) of the skin is characterized by intraepidermal adenocarcinoma cells, which contain clear cytoplasm and abundant mucin. Nearly all cases of mammary PD (MPD) are associated with underlying ductal carcinoma of the breast, whereas in the majority of cases of extramammary PD (EMPD) no underlying regional malignancy is identified. Mucins are high molecular weight glycoproteins produced by epithelial cells. Different mucin genes are expressed in various types of tissues such as mammary glands, intestinal mucosa, and adnexal structures of the skin. We studied the immunohistochemical expression of apomucin MUC1, MUC2, MUC5AC in MPD, and EMPD. MUC1 is commonly expressed in most cases of PD. MUC5AC is a unique mucin that is exhibited in the majority of cases of EMPD, but not in any MPD. Of the 13 patients with MPD who all had associated breast ductal carcinoma, both Paget cells and underlying ductal carcinoma exhibited the phenotype (MUC1+MUC2-MUC5AC-). This mucin phenotype is also expressed by Toker cells, which have been identified in the epidermis of five of 50 nipples in mastectomies without MPD. Of the three patients with perianal PD who all had associated rectal adenocarcinoma, Paget's cells expressed MUC2 constantly but expressed MUC1 and MUC5AC variably. Seven patients with intraepidermal vulvar PD and two patients with scrotal-penile PD had no identifiable underlying malignancy. Paget cells from all of these nine cases of EMPD expressed a uniform phenotype of mucin (MUC1+MUC2-MUC5AC+). One case of vulvar PD associated with underlying apocrine carcinoma had a phenotype (MUC1+MUC2-MUC5AC-) identical to that of normal apocrine glands. The skin appendage and Bartholin's glands from 20 normal-appearing vulvar skin samples and anal glands from 10 hemorrhoidectomies were also studied. Only Bartholin's gland expressed a mucin phenotype identical to that of intraepidermal EMPD. The results of the present study indicate that 1) MPD may arise from either mammary glands or epidermal Toker cells, 2) intraepidermal EMPD in the anogenital areas may arise from ectopic MUC5AC+ cells originating from Bartholin's or some other unidentified glands, and 3) unique expression of MUC2 in perianal PD indicates its origin from colorectal mucosa. We conclude that the study of mucin gene expression is useful in identifying the histogenesis of PD.

Characterization of mucin in gut lavage fluid obtained from inflammatory bowel disease

Gut lavage fluid, collected by the oral administration of an electrolyte lavage solution, was found to be an excellent and easily collectible source of abundant mucin. Furthermore, the biochemical features of mucin from patients with ulcerative colitis (UC) and Crohn's disease (CD) were investigated. The mucin was separated into four fractions by Sepharose CL-4B, Sepharose CL-2B, and DEAE Sephacel chromatography. Compared to healthy subjects, the total yields of mucin from ulcerative colitis patients were low due to a deficiency of neutral mucin, whereas those from Crohn's disease patients were high, mainly due to high-molecular-weight mucin. Fucose and sulfate content was low in ulcerative colitis, but only the former was low in Crohn's disease. The different biochemical features of mucin obtained from gut lavage fluid appear to reflect the mucosal pathological changes associated with inflammatory bowel disease.

Patients with pseudomyxoma peritonei associated with disseminated peritoneal adenomucinosis have a significantly more favorable prognosis than patients with peritoneal mucinous carcinomatosis

Pseudomyxoma peritonei (PMP) is a poorly understood condition characterized by disseminated intraperitoneal mucinous tumors, often with mucinous ascites. The term PMP has been applied historically as a pathologic diagnostic term to both benign and malignant mucinous neoplasms that produce abundant extracellular mucin, resulting in a variable and poorly predictable prognosis. A recent study reported a pathologic classification that separated patients into prognostically distinct groups, but the follow-up was relatively short. Long-term follow-up data were analyzed for a previously reported series of 109 patients with PMP to examine the prognostic utility of a pathologic classification system that divided patients into three groups: disseminated peritoneal adenomucinosis (DPAM), peritoneal mucinous carcinomatosis (PMCA), and peritoneal mucinous carcinomatosis with intermediate or discordant features (PMCA-I/D). Patients whose tumors were classified 25 DPAM (n = 65 patients) had disease that was characterized by histologically bland to low-grade adenomatous mucinous epithelium associated with abundant extracellular mucin and fibrosis, often with an identifiable appendiceal mucinous adenoma that was the source of the peritoneal lesions. Patients whose tumors were classified 25 PMCA (n = 30 patients) had disease that was characterized by peritoneal lesions that displayed the cytologic and architectural features of mucinous carcinoma associated with extracellular mucin, often with an identifiable invasive mucinous adenocarcinoma of the gastrointestinal tract. Patients whose tumors were classified 25 PMCA-I (n = 11 patients) had peritoneal lesions that combined the features of DPAM and PMCA derived from well differentiated mucinous adenocarcinomas associated with adenomas. Patients whose tumors were classified 25 PMCA-D (n = 3 patients) had markedly atypical appendiceal adenomas associated with peritoneal lesions similar to PMCA. Patients with DPAM had 5-year and 10-year survival rates of 75% and 68%, respectively (mean follow-up, 96 months; median follow-up, 104 months). Patients with PMCA and PMCA-I/D had a significantly worse prognosis, with 5-year and 10-year survival rates, respectively, of 50% and 21% for PMCA-I/D (mean follow-up, 58 months; median follow-up, 51 months) and 14% and 3% for PMCA (mean follow-up, 27 months; median follow-up, 16 months; P = 0.0001). The term PMP should be used only as a clinical descriptor for patients who have the syndrome of mucinous ascites accompanied by a characteristic distribution of peritoneal mucinous tumors with the pathologic features of DPAM. DPAM should be used as a pathologic diagnostic term for patients with the bland peritoneal mucinous tumors associated with ruptured appendiceal mucinous adenomas and PMP. These patients should not be diagnosed with carcinoma, because they have disease that is distinct pathologically and prognostically from PMCA.

CT appearance of disseminated peritoneal adenomucinosis.

Disseminated peritoneal adenomucinosis (DPAM) is a relatively rare cause of pseudomyxoma peritonei, marked by peritoneal lesions with abundant extracellular mucin and little cytologic atypia among exfoliated tumor cells, and usually associated with appendiceal adenomas. Peritoneal mucinous carcinomatosis (PMCA) also causes diffuse peritoneal tumor but is marked by neoplastic mucinous epithelium with cytologic features of carcinoma and associated with appendiceal, colon, gastric, or small bowel carcinoma. Compared with PMCA, DPAM has a different distribution of disease and a significantly better prognosis. DPAM is characterized by the lack of lymph node involvement, with primarily superficial peritoneal involvement, and a relatively benign, relapsing course over many years. Dominant primary masses may not be evident in DPAM. Despite considerable overlap in the two main causes of pseudomyxoma peritonei, there are features of the two that may help differentiate between them. We present the computed tomographic appearance of DPAM in a series of seven cases and emphasize characteristics of the disease.

Cutaneous myoepithelioma: an under-recognized cutaneous neoplasm composed of myoepithelial cells.

Benign and malignant neoplasms of myoepithelial cells comprise a rare but well-characterized group of tumors, among which myoepithelioma of the salivary glands is the best known. Extrasalivary examples of myoepithelioma also have been described in the breast, larynx, and retroperitoneum. Recently, myoepithelioma of the soft tissue also has been reported. According to this description, myoepithelioma and mixed tumors arising in the skin and subcutis represent points along a clinicopathologic spectrum of cutaneous and soft-tissue tumors. To the best of our knowledge, there has been only one case report of an entirely cutaneous myoepithelioma in the literature. We report herein five additional examples of purely myoepithelial tumors located exclusively in the dermis. Histopathologically, the neoplasms were well-circumscribed dermal lesions composed of fascicles of spindle cells with eosinophilic cytoplasm and ovoid-to spindle-shaped nuclei. Focally, neoplastic aggregations of more epithelioid cells representing large round cells with abundant pale cytoplasm arranged in solid clusters, cords, or strands were also seen. Ductal differentiation was not identified in either of these solid aggregations of epithelioid cells or in the fascicles of spindle-shaped cells. Nuclear pleomorphism in epithelioid and spindle-cell areas was mild, and mitotic figures were very sparse. In some cases, small, necrotic areas were seen within the solid aggregations of spindle-shaped cells. Neoplastic stroma was scant and composed of fibrillary collagen and abundant mucin. In one case, the stroma consisted of clusters of mature adipocytes intermingled with fascicles of myoepithelial cells. Areas of chondroid or osteoid metaplasia were not seen in any of the cases. Immunohistochemically, neoplastic cells expressed positivity for muscle specific actin (HHF35), alpha smooth muscle actin (IA4), S-100 protein, glial fibrillary acidic protein (GFAP), and epithelial membrane antigen (EMA), whereas stains for pan-cytokeratin (MNF116) were focal and weak. The findings in this report expand the clinical and histopathologic spectrum of cutaneous myoepithelioma, an under-recognized cutaneous neoplasm of myoepithelial cells.