RESUMEN
We examined 38 appendectomies with diagnoses of mucocele, diverticulum, or adenoma to study the coincidence of appendiceal diverticula and appendiceal low-grade mucinous neoplasms and to examine the possible role of diverticula in the pathogenesis of pseudomyxoma peritonei. Invasive adenocarcinomas and retention cysts were excluded (six cases). Cases were classified as adenomas or mucinous tumors of unknown malignant potential, with or without diverticula. Medical records were reviewed for multiple parameters, including presenting symptoms, presence of pseudomyxoma peritonei, and presence of associated malignancies. Binomial statistics were used to calculate the probability that the observed prevalence of low-grade mucinous neoplasms and diverticula together was significantly different from the expected prevalence of diverticula or low-grade mucinous neoplasms alone, using historical controls from the literature. Twenty-five percent of the total cases (8 of 32) contained both a low-grade mucinous neoplasm (7 cystadenomas and 1 mucinous tumor of unknown malignant potential) and a diverticulum. Thus, 8 of 19 low-grade mucinous neoplasms (42%) were associated with diverticula. Of the appendices with both low-grade mucinous neoplasms and diverticula, three contained dissecting acellular mucin within the appendiceal wall, four showed diverticular perforation, and one had pseudomyxoma peritonei associated with the ruptured diverticulum. A significant percentage (P < .001) of cases contained low-grade mucinous neoplasms and diverticula together. The case of coexistent low-grade mucinous neoplasm, diverticulum, and pseudomyxoma peritonei suggests that diverticula could play a role in the pathogenesis of pseudomyxoma peritonei. This could occur either by involvement of preexisting diverticula by the neoplasm or by distention of the appendiceal lumen by mucin, leading to increased intraluminal pressure and subsequent diverticulum formation at a weak area in the wall. Either mechanism might allow low-grade mucinous neoplasms to penetrate the appendiceal wall more easily.
Asunto(s)
Neoplasias del Apéndice/patología , Apéndice/patología , Cistoadenoma Mucinoso/patología , Divertículo/patología , Adulto , Anciano , Apendicectomía , Neoplasias del Apéndice/complicaciones , Cistoadenoma Mucinoso/complicaciones , Divertículo/complicaciones , Humanos , Persona de Mediana Edad , Neoplasias Peritoneales/etiología , Neoplasias Peritoneales/patología , Seudomixoma Peritoneal/etiología , Seudomixoma Peritoneal/patología , Estadística como AsuntoRESUMEN
In normal somatic cells, the methylation pattern of DNA is stably maintained by DNA (cytosine-5-)-methyltransferase (DNA methyltransferase). Increased expression of DNA methyltransferase has been detected in many types of human cancer and has been thought to play an important role in tumorigenesis. In our study, we developed a standardized reverse transcription-polymerase chain reaction (RT-PCR) assay to determine the mRNA levels of DNA methyltransferase in rhabdomyosarcoma, the most common soft tissue cancer in children. Using this assay, expression of DNA methyltransferase was analyzed for 32 rhabdomyosarcomas and 12 normal skeletal muscle samples. All tumor samples, of which 18 were embryonal and 14 were alveolar subtype, showed increased expression of DNA methyltransferase after normalization to beta-actin. Compared to normal skeletal muscle, the average increase of DNA methyltransferase expression was 6.7-fold (6.7 +/-()0.96) in the embryonal tumors and 3.7-fold (3.7 +/- 0.46) in the alveolar rhabdomyosarcomas. The difference in the average increase of the DNA methyltransferase expression was statistically significant in the 2 rhabdomyosarcoma subtypes, which have distinct etiologies and clinical behaviors. Our results are consistent with previous reports that an increase in DNA methyltransferase activity is associated with neoplastic transformation; however, the role of increased DNA methyltransferase expression in the development and progression of rhabdomyosarcoma needs to be investigated in future studies.
Asunto(s)
ADN (Citosina-5-)-Metiltransferasas/metabolismo , Proteínas de Homeodominio , Músculo Esquelético/enzimología , Rabdomiosarcoma/enzimología , Adolescente , Fusión Artificial Génica , Niño , Preescolar , Proteínas de Unión al ADN/metabolismo , Proteína Forkhead Box O1 , Factores de Transcripción Forkhead , Humanos , Inmunohistoquímica , Proteínas Musculares/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Factor de Transcripción PAX3 , Factor de Transcripción PAX7 , Factores de Transcripción Paired Box , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Rabdomiosarcoma/etiología , Factores de Transcripción/metabolismoRESUMEN
The differentiation of graft-verus-host disease (GVHD) from erythema multiforme (EM) presents a common diagnostic challenge in skin biopsy specimens from patients who have received patients allogeneic bone marrow transplants. The presence of gastrointestinal involvement might be the only way to make a diagnosis of GVHD in these cases. In the absence of liver function tests, gastrointestinal biopsy, or molecular techniques such as microsatellite DNA analysis, the presence of intraepidermal bile pigment might prove helpful in elucidating hyperbilirubinemia and allowing a pathologist to favor a diagnosis of GVHD over EM. Routinely processed archival tissue from 50 cases of GVHD (42 Caucasian and 8 of unknown race) and 50 cases of EM (31 Caucasian and 19 of unknown race) was examined for pigmentation. Intraepidermal pigmentation was stained for bile pigment and melanin. Among the intraepidermal EM lesions, 4 (8%) stained for intracorneal melanin, but none stained for bile pigment. Among the intraepidermal GVHD lesions, 8 (16%) stained for intracorneal melanin, but 3 (6%) stained for intracorneal bile pigment. In addition, 13 (26%) GVHD lesions and 9 (18%) EM lesions showed melanosis with melanin in all layers of the epidermis as well as within papillary dermal melanophages. Thus, when presented with a differential diagnosis of GVHD versus EM, the presence of intraepidermal bile pigment might suggest liver involvement and a diagnosis of GVHD.