Extreme particle acceleration in the microquasar Cygnus X-3.

Super-massive black holes in active galaxies can accelerate particles to relativistic energies, producing jets with associated gamma-ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares. Apart from an isolated event detected in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four gamma-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary that sporadically produces radio jets). There is a clear pattern of temporal correlations between the gamma-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

Polypoid clear cell acanthoma of the scalp.

Clear cell acanthoma (CCA) is a rare, benign epithelial tumor most frequently found on the lower extremities. Its clinical appearance may vary considerably, and cases of multiple lesions have been reported. The diagnosis is made by viewing the characteristic histologic features. This case describes an unusual scalp lesion that clinically and histologically shows unique polypoid features.

Acquired vulvar lymphangiomas: a sequela of radiation therapy.

Lymphangiomas of the vulva are rare clinical entities. Acquired or secondary lymphangiomas have characteristically been reported after radiation therapy for cervical carcinoma and appear on the vulva years after this treatment. Local surgery, scrofuloderma, and Crohn's disease may also damage vulvar lymphatic flow and lead to the development of vulvar lymphangiomas. We report a case of acquired vulvar lymphangiomas that occurred in a patient 15 years after she received radiation therapy for squamous cell carcinoma of the uterine cervix.

Migratory poliosis: A forme fruste of alopecia areata?

We describe a 19-year-old African-American man with a 14-year history of migratory poliosis. We suggest that this phenomenon may represent a forme fruste of alopecia areata.

Malignant melanoma arising in a seborrheic keratosis.

We report a case of malignant melanoma associated with seborrheic keratosis. This has been reported rarely in the literature, with disagreement regarding whether it is coincidental or whether malignant transformation occurs. Because seborrheic keratoses are common and association with malignant melanoma is very rare, we conclude that the association is coincidental. However, because of the association of other malignancies, a biopsy of any suspect or changing seborrheic keratosis is essential.

Elastic tissue in scars and alopecia.

A recent report suggests that elastic fibers appear in scars in a time-dependent fashion. This observation prompted our investigation, because we have found elastic tissue stains helpful in determining the pattern of scarring in cases of permanent alopecia. We carried out this investigation to determine if the Verhoeff-Van Gieson (VVG) elastic stain can reliably differentiate scarred from non-scarred dermis and to test our hypothesis that elastic stained sections are helpful in distinguishing lichen planopilaris (LPP) from lupus erythematosus (LE), central progressive alopecia in black females ("follicular degeneration syndrome" and "hot comb alopecia" are other terms used to describe this condition) and classic ivory white idiopathic pseudopelade. We studied histological sections from surgical scars of known duration, stained with the VVG elastic stain and VVG-stained sections of scalp biopsies from patients with established lesions of permanent alopecia. In most cases, both vertical and transverse sections were examined. In every case, the VVG stain clearly differentiated scar from the normal surrounding dermis. Distinct patterns of elastic tissue allowed for correct classification in most of the well-established cases of permanent alopecia studied. We determined that the Verhoeff-Van Gieson stain is an excellent stain to evaluate the pattern of scarring in cases of permanent alopecia and elastic tissue stains may be helpful in the histological evaluation of alopecia.

Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: a controlled clinical trial.

CONTEXT: Endotracheal intubation (ETI) is widely used for airway management of children in the out-of-hospital setting, despite a lack of controlled trials demonstrating a positive effect on survival or neurological outcome. OBJECTIVE: To compare the survival and neurological outcomes of pediatric patients treated with bag-valve-mask ventilation (BVM) with those of patients treated with BVM followed by ETI. DESIGN: Controlled clinical trial, in which patients were assigned to interventions by calendar day from March 15, 1994, through January 1, 1997. SETTING: Two large, urban, rapid-transport emergency medical services (EMS) systems. PARTICIPANTS: A total of 830 consecutive patients aged 12 years or younger or estimated to weigh less than 40 kg who required airway management; 820 were available for follow-up. INTERVENTIONS: Patients were assigned to receive either BVM (odd days; n = 410) or BVM followed by ETI (even days; n = 420). MAIN OUTCOME MEASURES: Survival to hospital discharge and neurological status at discharge from an acute care hospital compared by treatment group. RESULTS: There was no significant difference in survival between the BVM group (123/404 [30%]) and the ETI group (110/416 [26%]) (odds ratio [OR], 0.82; 95% confidence interval [CI], 0.61-1.11) or in the rate of achieving a good neurological outcome (BVM, 92/404 [23%] vs ETI, 85/416 [20%]) (OR, 0.87; 95% CI, 0.62-1.22). CONCLUSION: These results indicate that the addition of out-of-hospital ETI to a paramedic scope of practice that already includes BVM did not improve survival or neurological outcome of pediatric patients treated in an urban EMS system.

A 5-year time study analysis of emergency department patient care efficiency.

STUDY OBJECTIVES: We conducted a 5-year time study analysis of emergency department patient care efficiency. Our specific aims were (1) to calculate the main ED patient care time intervals to identify areas of inefficiency, (2) to measure the effect of ED and inpatient bed availability on patient flow, (3) to quantitatively assess the effects of administrative interventions aimed at improving efficiency, and (4) to evaluate the relationship between waiting times to see a physician and the number of patients who leave without being seen (LWBS) by a physician. METHODS: Seven 1-week ED patient flow time studies were conducted from September 1993 to July 1998 using identical study design and methodology. Patients presenting with complaints of chest pain, abdominal pain, vaginal bleeding, and extremity injury were included to represent the level of severity of patient conditions seen in our Los Angeles County hospital ED. The calculated time intervals representing the main phases of evaluation and treatment were (1) triage presentation to completion of registration, (2) completion of registration to ED treatment area entry, (3) ED treatment area entry to initial medical assessment, (4) triage presentation to initial medical assessment, (5) initial medical assessment to disposition order, and (6) disposition order to patient discharge from the ED. Total ED lengths of stay (LOS) were also calculated as overall measures of efficiency. Time intervals were compared depending on the availability of ED and hospital inpatient beds. The effects of administrative interventions on the specific time intervals were assessed. The relationship between the median waiting time to see a physician and the number of LWBS patients was evaluated. Administrative interventions were implemented by a special interdepartmental continuous quality improvement committee. Interventions were aimed at specific sources of delay and inefficiency identified by the time studies. RESULTS: Eight hundred twenty-six patients were included in the 7 time studies. The unavailability of ED and inpatient beds was associated with significant delays. There was a significant reduction of the median total ED LOS from 6.8 hours to 4.6 hours over the first 5 periods, presumably resulting from the administrative interventions. Median total ED LOS, however, increased from 4.6 hours to 6.0 hours during the last 2 periods, possibly as a result of an increase in our ED patient census and reductions in both nursing and physician staffing imposed by the recent Los Angeles County fiscal crisis. The number of LWBS patients was closely correlated to waiting time to see a physician ( r =0.79, beta=5.20, P =.033). CONCLUSION: Time studies are an effective method of identifying areas of patient care delay. In our ED, targeted administrative interventions apparently reduced the total ED LOS and improved overall efficiency. Despite initial decreases in ED LOS, efficiency appeared to be adversely affected by reductions in nursing and physician staffing and increases in our patient census. The strength of the relationship between waiting times to see a physician and the number of LWBS patients suggests that decreasing waiting times may reduce the number of LWBS patients.

Commentary

[McCollough M: Progress toward eliminating Haemophilus influenzae type b disease among infants and children-United States, 1987-1997 [commentary]. Ann Emerg Med July 1999;34:110-111.]

Primary cutaneous B-cell lymphoma.

A 63-year-old woman presented with a single plaque on her left earlobe that was shown to be a B-cell lymphoma on histopathologic examination. Immunohistochemical studies on the paraffin-embedded tissue and flow cytometry of fresh tissue helped characterize the neoplasm. She had no other systemic involvement and a diagnosis of primary cutaneous B-cell lymphoma was made. This neoplasm has, in general, a good prognosis with excellent response to radiation therapy, polychemotherapy, or both.

Acquired perforating dermatosis in a patient with chronic renal failure and diabetes mellitus.

Perforating disorders in patients with chronic renal failure (CRF), diabetes mellitus (DM), or both, may resemble any or all of the four classic cutaneous perforating disorders. However, due to the highly variable and overlapping histologic appearance of the lesions in patients with CRF, DM, or both, it may be useful to categorized these lesions as a distinct, yet encompassing process, termed by Rapini as acquired perforating dermatosis. We describe a patient with both CRF and DM with acquired perforating dermatosis.

Primary anetoderma.

Primary anetoderma is a rare disorder characterized by sac-like herniations and depressions in previously normal skin. On histologic examination, elastic fibers are destroyed by an inflammatory infiltrate. We describe a striking case of primary anetoderma and review the classification, differential diagnosis, causes, and treatment.

Cutaneous parachordoma. A light microscopic and immunohistochemical report of two cases and review of the literature.

Parachordomas are rare cutaneous tumors that show virtually identical histologic findings to chordomas. Therefore, the major differential diagnosis in a case of parchordoma is metastatic chordoma. Parachordomas are benign neoplasms and most often develop on the extremities adjacent to tendons, synovium or osseous structures, as opposed to chordomas, which are malignant tumors located along the craniospinal axis. While recurrences may occur in cases of parachordoma, metastases have not been reported. In this report, two cases of parachordomas are reported and the literature reviewed. By light microscopy, parachordomas show eosinophilic bands of fibrous tissue separating lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) admixed with more epithelioid cells in a myxoid stroma. Parachordomas and chordomas share immunohistochemical and ultrastructural features. Both stain with S-100 protein and vimentin, and ultrastructurally both demonstrate cytoplasmic vacuoles, intermediate filaments, pinocytotic vesicles, celljunctions, and cytoplasmic membranes with microvillous processes. Chordomas more frequently express cytokeratin (98% vs. 66% in parachordomas) and epithelial membrane antigen (90% vs. 20% in parachordomas) and chordomas have a larger number of rough endoplasmic reticulum-mitochondrial complexes. Thus, positive staining with epithelial membrane antigen and the identification of a large number of rough endoplasmic reticulum-mitochondrial complexes are suggestive of metastatic chordoma. However, the definitive distinction remains a clinical one after appropriate radiologic studies of the skull and spinal chord.

Alabaster skin after carbon dioxide laser resurfacing with histologic correlation.

BACKGROUND: Carbon dioxide laser resurfacing has gained popularity as a relatively safe and effective method of facial rejuvenation. Original reports describe mostly reversible side effects and a low incidence of scarring. Only very recently have reports of delayed hypopigmentation surfaced. This effect is not visible until several months after resurfacing, and most likely represents a permanent change. OBJECTIVE: To provide an additional clinical description of the complication of delayed hypopigmentation along with the first published histologic correlation. METHODS: Clinical records along with a preprocedure and 7-month postprocedure full-thickness skin biopsy were used for this report. RESULTS: This patient experienced a striking leukoderma 6 months after a full facial carbon dioxide laser resurfacing procedure done for widespread actinic keratoses. There was a zone of dermal fibrosis extending approximately 0.4 mm on the postprocedure biopsy. Comparison of the preprocedure and postprocedure biopsies revealed no difference in the number of melanocytes by MART-1 immunohistochemical staining, but there was a significant decrease in epidermal melanin as determined by Fontana-Mason staining. CONCLUSION: This patient experienced a profound expression of an increasingly recognized and reported complication of carbon dioxide laser resurfacing. Histologic correlation is similar to the results previously reported after phenol chemical peels, demonstrating a normal number of melanocytes but a decrease in epidermal melanin.

Vesiculo-bullous dermatomyositis.

Cutaneous manifestations of dermatomyositis (DM) commonly include Gottron's papules, cuticular erythema and telangiectasia, periorbital edema with a "heliotrope" rash, a papulosquamous eruption of the hairline, face, and trunk, as well as poikiloderma. Very few references can be found concerning vesicular and bullous lesions, however. We present two patients with dermatomyositis who manifested vesicular and bullous lesions who were initially misdiagnosed. Although rare, it is important to recognize this form of DM to avoid misdiagnosis. Furthermore, in some cases, vesiculo-bullous DM may portend a poor prognosis.

Periductal mastitis. Masquerading as carcinoma.

Periductal mastitis (mammary duct ectasia) is a little appreciated, often unrecognized entity that may present to the dermatologist. We present our experience with this disease and hope to familiarize the reader with a condition not well known to most dermatologists. Periductal mastitis is a benign mammary duct disease that begins with periductal inflammation and progresses to ductal dilatation with minimal inflammation (ductal ectasia). The clinical and radiographic appearance of this disease can be indistinguishable from carcinoma of the breast.

Rheumatoid neutrophilic dermatitis.

Rheumatoid neutrophilic dermatitis (RND) is a rare cutaneous finding in patients with severe rheumatoid arthritis or with high-titer rheumatoid factors. Most commonly, these lesions are erythematous papules or plaques distributed symmetrically on extensor surfaces. On histologic examination a dense dermal neutrophilic infiltrate without vasculitis is apparent. The pathogenesis of RND is unclear, and few treatments are known. With careful clinical and histologic examination, RND may be differentiated from the wide array of other cutaneous findings in rheumatoid arthritis.