PTF 11kx: a type Ia supernova with a symbiotic nova progenitor.

There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumstellar material are detected, and the SN ejecta are seen to interact with circumstellar material starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi.

Acantholysis and spongiosis are associated with loss of syndecan-1 expression.

BACKGROUND: Syndecan-1, a heparan sulfate proteoglycan present on the membrane of keratinocytes, functions in intercellular adhesion. Acantholysis and spongiosis are both characterized by diminished intercellular adhesion that may lead to blister formation. In spongiotic conditions, desmosomal stretching occurs prior to cell separation while in acantholytic conditions, cell separation occurs without stretching. While many of the structural relationships have been described, the molecular interactions regulating keratinocyte to keratinocyte adhesion are not yet fully understood. METHODS: Sections from ten cases of Grover's disease, two pemphigus vulgaris, one pemphigus foliaceus, one bullous pemphigoid, two herpes simplex, and ten spongiotic dermatitis were stained with BB-4, a monoclonal anti-syndecan-1 antibody. RESULTS: Nine of ten Grover's, all three pemphigus, and both herpes cases showed absent or markedly decreased syndecan-1 expression by acantholytic keratinocytes, with a sharp delineation from adjacent unaffected skin. The remaining Grover's case showed moderate loss of syndecan-1 expression. The pemphigus foliaceus case showed retention of staining along the basal cell layer, but expression was lost in the mid stratum spinosum. All ten spongiotic cases showed a diffuse mild decrease in staining, with loss of syndecan-1 expression surrounding microvesicles. Bullous pemphigoid, as expected, did not show loss of syndecan expression. CONCLUSIONS: The loss of syndecan-1 expression evident in acantholytic conditions and, to a lesser extent in spongiotic conditions, may contribute to the decreased intercellular adhesion characteristic of these lesions.

The coexistence of low-grade mucinous neoplasms of the appendix and appendiceal diverticula: a possible role in the pathogenesis of pseudomyxoma peritonei.

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.

Syndecan-1 expression is decreased with increasing aggressiveness of basal cell carcinoma.

Syndecans, a family of cell-surface proteoglycans of which syndecan-1 is the prototypical member, play an important role in limiting tumor growth and invasive capacity through their actions as receptors for growth factors and extracellular matrix. Cutaneous biopsy specimens of basal cell carcinoma, including superficial, nodular, infiltrative, and morpheic subtypes, were assessed regarding the pattern of syndecan-1 expression. We found that with increasing aggressiveness of basal cell carcinomas, syndecan-1 expression is lost from the surface of the neoplastic cells. However, within the dermis, which is normally devoid of syndecan-1 expression, immunopositivity for syndecan-1 is present in areas adjacent to aggressive tumors. This pattern of staining indicates that syndecan-1 expression is produced by stromal cells rather than being shed by the carcinoma cells into the stroma.

Strong immunostaining for myogenin in rhabdomyosarcoma is significantly associated with tumors of the alveolar subclass.

Rhabdomyosarcomas are a heterogeneous group of tumors with respect to their molecular basis, degree of differentiation, histology, and clinical behavior. Because of the wide variation of tumor morphology, it is often difficult to distinguish between the distinct subtypes of rhabdomyosarcomas. By using cryosections of tumor specimens and immunohistochemistry, in the present study we show that strong expression of myogenin in rhabdomyosarcoma is associated with alveolar histology (P = <0.0001, Fisher's exact test). Although staining for myogenin was observed in 22 of 26 rhabdomyosarcomas, all alveolar rhabdomyosarcomas (nine of nine) showed high levels of staining for myogenin, as defined by the frequency and intensity of staining of the tumor cells. The staining pattern suggests that the tumor cells are clonally derived from myogenin-positive progenitor cells. In contrast, most embryonal rhabdomyosarcomas (13 of 15) were either negative or showed a low level of staining for myogenin. In these tumors a larger proportion of tumor cells were distinctly negative for myogenin. Six of seven alveolar rhabdomyosarcomas that strongly stained for myogenin were also positive for Pax3-7/Forkhead (FKHR) by polymerase chain reaction/reverse transcriptase-polymerase chain reaction. One of two embryonal rhabdomyosarcomas that strongly stained for myogenin was retrospectively found to be positive for Pax3/FKHR transcripts. Quantitative analysis for myogenin by Western blotting using a smaller subset of rhabdomyosarcomas revealed that in general there was a good correlation between immunohistochemical staining and Western blotting (P = 0.01, Pearson Correlation), although the former technique was more sensitive for detecting tumors with low levels of the protein. On average, alveolar rhabdomyosarcomas expressed at least threefold more myogenin than embryonal rhabdomyosarcomas. Our data show that staining for myogenin will be a simple, rapid, and accurate adjunct for distinguishing between alveolar and embryonal rhabdomyosarcomas. We propose that embryonal rhabdomyosarcomas result from an early block in myogenesis, before the expression of myogenin. In contrast, we propose that alveolar rhabdomyosarcomas either originate from a late block in myogenesis (after expression of myogenin) or that the pathological mechanisms involved in these neoplasms also induce strong expression of this protein.

Primary basal cell carcinoma of the middle ear presenting as recurrent cholesteatoma.

OBJECTIVE: This study aimed to sensitize the practitioner to the unusual presentation of basal cell carcinoma in a recurrent cholesteatoma mass. STUDY DESIGN: The study design was a case report format. SETTING: The study was conducted at a tertiary referral hospital. PATIENT: The patient studied was a contralaterally anacusic veteran. INTERVENTION: Interventions were excision of cholesteatoma and withholding of adjunctive radiation. CONCLUSION: Primary basal cell carcinoma may present in a revision cholesteatoma field.

Increased DNA methyltransferase expression in rhabdomyosarcomas.

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.

Enzyme-linked immunoassay for respiratory syncytial virus is not predictive of bronchiolitis in sudden infant death syndrome.

Although respiratory syncytial virus (RSV)-infected infants may present with apnea, the role that RSV plays in sudden infant death syndrome (SIDS) is speculative. To determine whether RSV is associated with bronchiolitis in these patients, we examined histologic sections of lungs from 41 apparent SIDS cases and compared the results with those of enzyme-linked immunofluorescent assay (EIA) from nasal washings. Bronchiolitis was defined by a bronchiolar inflammatory cell infiltrate plus epithelial necrosis. A positive EIA was associated with bronchiolitis in 8 instances, compared with 6 having a positive EIA and negative histology, 14 having a negative EIA and positive histology, and 13 having EIA and histology both negative. These results yield a predictive value of a positive test of 57% and a predictive value of a negative test of 48% (P > .9 by chi square analysis). Although RSV of the upper respiratory tract may be related to SIDS, our results indicate that EIA of nasal washings is not predictive of bronchiolitis, and we recommend other means of verification of histologic results.

Intraepidermal bile pigment in skin biopsy specimens for graft-versus-host disease versus erythema multiforme.

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.