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.

Intracytoplasmic retention of type VII collagen and dominant dystrophic epidermolysis bullosa: reversal of defect following cessation of or marked improvement in disease activity.

It has been recently shown that the presence of perinuclear "stellate bodies" within the epidermis in patients with a form of dominant dystrophic epidermolysis bullosa named "transient bullous dermolysis of the newborn" corresponds to collections of type VII collagen. To determine the temporal relationship of this unique immunohistochemical defect with course of clinical disease activity, we have longitudinally studied the expression of two epitopes of type VII collagen (LH 7:2; L3d) in nine patients in four such kindreds by immunofluorescence and immunoelectron microscopic technique. In every infant so studied at the time of active blistering, type VII collagen was detectable primarily within basilar and, to a lesser extent, suprabasilar keratinocytes. In contrast, type VII collagen was detectable solely in linear array along the dermoepidermal junction in skin from each patient following complete cessation or at least marked diminution of visible clinical disease activity. These findings support the hypothesis that the temporary mechanical fragility and blistering of the skin in infants with this rare subset of dominant dystrophic epidermolysis bullosa reflect the presence of reduced amounts of type VII collagen along the dermoepidermal junction, and that this diminution may be the result of either a delay in transport and integration of type VII collagen from basilar keratinocytes into the skin basement membrane or excessive phagocytosis of type VII collagen.

Pseudocyst of the auricle associated with trauma.

A pseudocyst of the auricle (benign idiopathic cystic chondromalacia) is an intracartilaginous cystic swelling of the anterior auricle. The cause is uncertain, and most patients deny any history of inflammation or trauma. A patient had antecedent trauma and a fracture in the conchal cartilage; a simple surgical procedure was used to treat this patient.

Acute cutaneous reactions to docetaxel, a new chemotherapeutic agent.

BACKGROUND: Docetaxel (RP 56976) is a new chemotherapeutic agent that has shown promise in a number of animal studies and is currently undergoing phase I and phase II trials. Early in the phase I trials, it was noted that a significant number of patients were experiencing a variety of cutaneous complaints, so we elected to prospectively evaluate the cutaneous reactions occurring during the first three courses of therapy in the first 12 patients enrolled for phase I chemotherapy at our institutions. OBSERVATIONS: All but one patient had some type of cutaneous eruption over the three courses of therapy. Of the 27 evaluable courses of docetaxel given, 19 (70%) resulted in a cutaneous eruption with four (21%) being asymptomatic and 15 (79%) being at least mildly symptomatic. The most common reaction seen was characterized by discrete erythematous to violaceous patches or edematous plaques similar to acral erythema. CONCLUSION: Although a majority of patients receiving docetaxel experience some degree of cutaneous reaction, the eruptions are usually mildly symptomatic and almost always self-limiting.

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.]

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.

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.

A pigmented scalp nodule: malignant blue nevus.

The malignant blue nevus is an aggressive dermal melanocytic neoplasm. The lesion occurs most frequently on the scalp of men in their fifth decade of life, often metastasizes to the regional lymph nodes, and commonly results in fatality. Controversy exists as to whether this lesion is a malignant melanoma in the dermis or a separate neoplasm arising in the architecture of a cellular blue nevus. The lesion is treated with wide local excision and close monitoring for the occurrence of metastatic disease.

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.

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.

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.

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.

Parelaphostrongylus tenuis in Maine moose and the possible influence of faulty Baermann procedures.

Efficacy of cleaning Baermann apparati was evaluated to determine if larvae are retained on glassware after evaluating white-tailed deer (Odocoileus virginianus) fecal samples containing Parelaphostrongylus tenuis. Residual P. tenuis larvae were recovered from 7 (11.7%) of 60 Baermann apparati cleaned with soap and tap water. Of 295 moose (Alces alces) fecal samples collected in central and northern Maine, only one contained protostrongylid larvae. Our data do not support the hypothesis that recent increases in Maine's moose population can be attributed to moose becoming a suitable host to P. tenuis.

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.

Vertical and transverse sections of alopecia biopsy specimens: combining the two to maximize diagnostic yield.

BACKGROUND: Traditional vertical sections of scalp biopsy specimens contain few hair follicles. For this reason transverse sections of scalp biopsy specimens have been advocated. Both methods have advantages and disadvantages. We have developed a simple method that we believe offers the best of both methods. OBJECTIVE: Our purpose was to assess the impact of combining vertical and transverse sections of scalp biopsy specimens. METHODS: Two 4 mm punch biopsies are performed. One specimen is bisected vertically: half for hematoxylin-eosin (H-E) staining, half for direct immunofluorescence. The second specimen is bisected transversely and submitted for H-E. The three pieces of tissue for H-E staining are embedded in a single cassette. RESULTS: Because a biopsy specimen for direct immunofluorescence is commonly obtained in cases of alopecia, our method does not add a surgical procedure. All three pieces of tissue for H-E staining are embedded in a single paraffin block. Therefore the cost of histologic interpretation is not increased. Our diagnostic yield improved. Transverse sections were superior in cases of lupus erythematosus and lichen planopilaris with focal follicular involvement. Features of the follicular degeneration syndrome were also best demonstrated in transverse sections. Interface changes, lupus panniculitis, miniaturized hairs, and trichomalacia were better demonstrated in vertical sections. CONCLUSION: Our method exploits the advantages of both vertical and transverse sections and improves diagnostic yield without increasing cost.