The asteroid body of lobomycosis

Lobomycosis

Lobomycosis is a rare chronic fungal infection of the subcutaneous tissue found in South America, mainly in Brazil. It is caused by Lacazia loboi. Its clinical manifestations are dermal nodules, either lenticular or in plaques, and keloidlike lesions that can resemble nodular leprosy or leishmaniasis, other subcutaneous mycoses (sporotrychosis, chromomycosis, paracoccidioidomycosis), keloids, and malignant tumors. Diagnosis is made by the histopathological findings of the fungus. For treatment, surgical removal of the lesions, followed by itraconazole and clofazimine for disseminated lesions, has been used with variable results.

Asteroid body in sporotrichosis. Yeast viability and biological significance within the host immune response

The asteroid body in Sporotrichosis (AB) is a characteristic structure that allows diagnosis in lymphangitic presentations and whose generation and composition is not fully understood. Our study focused on the biological relationship between the yeast and host elements present in the AB. Indirect immunofluorescence showed that on ABs obtained from naturally infected individuals there were antigenically related IgG and IgM molecules in the spikes of the radiated crowns. However, there were differences in the pattern of distribution for each immunoglobulin isotypes. The yeast cells located at the center of the ABs were viable, as shown by the generation of germ tubes and conidial formation after 36-48 hours of incubation at 22 degrees C. The central yeast could divide and proliferate even in the ABs that had been pre-treated with specific anti-Sporothrix schenckii serum and fresh complement. The data suggests that AB in sporotrichosis might be a resistance structure which uses the host immune molecules to the advantage of the yeast.

Lacaziose (doença de Jorge Lobo): revisão e atualização

Lacaziose ou doença de Jorge Lobo é micose crônica, granulomatosa, causada por implantação traumática do fungo Lacazia loboi - patógeno não cultivável até o presente - nos tecidos cutâneo e subcutâneo, manifestando-se clinicamente por lesões nodulares queloidianas predominantes, envolvendo sobretudo pavilhões auriculares, face, membros superiores e inferiores, e não comprometendo as mucosas. A maioria dos casos humanos está registrada em países da América do Sul. Entretanto, a enfermidade apresenta aspectos epidemiológicos destacados, como o aparecimento em tribo Caiabi, no Brasil Central e em mamíferos não humanos, golfinhos de duas espécies (Tursiops truncatus e Sotalia guianensis) capturados na costa da Flórida (EUA), na foz do rio Suriname, na costa de Santa Catarina (Brasil), no golfo de Gasconha (baía de Biscaia-Europa), com manifestações cutâneas e achados histopatológicos muito similares às encontradas no homem. O artigo objetiva abordar características do fungo e sua taxonomia, e aspectos históricos, ecoepidemiológicos, clínicos, imuno-histoquímicos, histopatológicos, ultra-estruturais e terapêuticos.

Structural similarities between hematoidin crystals and asteroid bodies: evidence of lipid composition

Hematoidin crystals (HC) are found in tissues where extravasated erythrocytes undergo degradation. Previous studies have determined that hematoidin is composed, in part, of a bilirubin-like pigment. In a previous study (Papadimitriou and Drachenberg, Ultrastruct. Pathol. 16, 413-421, 1992), we demonstrated that giant cell asteroid bodies (AB) are formed by membrane lipid bilayers. We evaluated three cases in which HC developed within splenic infarcts. The crystals were analyzed by light microscopy (LM), electron microscopy (EM), and X-ray microanalysis. A case of sarcoidosis with multiple epithelioid granulomas containing AB was studied for comparison. By LM the HC demonstrated intense, golden-color, fine threads, both intracellularly and extracellularly, in small and large clusters, and in radiating, star-shape patterns ranging in size from 2 to 200 microm. By EM the HC were composed of a core of empty clefts, consistent with dissolved lipids, suggestive of cholesterol crystals, and were surrounded by myelinoid membrane aggregates. The AB showed by LM significant morphological similarities with the intracellular HC. By EM, the AB were composed of a core of dense phospholipid bilayer tubes surrounded by a halo of myelinoid membranes. No accumulation of specific elements was found in either HC or AB by X-ray microanalysis. HC and AB show a similar star-shape morphology by both LM and EM. We postulate that this shape is due to the physicochemical properties of the accumulated lipids which originate from superfluous cell membranes created during cell fusion in the case of AB and after cellular (predominantly red cell) breakdown in the case of HC. The golden color of the HC likely results from adsorption of hydrophobic bilirubin-like pigments left over from erythrocyte breakdown into the accumulated lipids. Thus, this study shows two different (patho)physiological processes that lead to a markedly similar morphological end-product and provides further support to our proposed mechanism for AB formation.