HISTOPLASMOSIS. (Fig 35-15). This disease is caused by Histoplasma capsulatum. Found throughout the world in temperate areas, Histoplasma capsulatum is a saprophytic fungus that grows in the soil, prevalently in soil of caves inhabited by bats. The disease is transmitted by the inadvertent inhalation of the spores. Epidemics have occurred through exploring infested caves or cleaning sites where chicken excrement (guano) may be present. A benign clinical form that may leave a calcified nodule in the lung similar to that of tuberculosis mimics the common cold. Primary infection, the most severe form of the disease, can disseminate and involve the reticuloendothelial system. Mucocutaneous nodules and granulomas may be seen. In AIDS the disease is seen in its most severe form. Primary cutaneous histoplasmosis occurs and is caused by direct inoculation. It is a nodular or indurated ulcer with accompanying lymphadenopathy. Occasionally an allergic response has been seen appearing as urticaria or as erythema annulare centrifugum. The diagnosis is accomplished by demonstrating the small intracellular histoplasma in sputum, bone marrow, or biopsy specimens. Treatment is done with ketoconazole or itraconazole.
COCCIDIOIDOMYCOSIS OR SAN JOAQUIN VALLEY FEVER This disease is caused by Coccidioides immitis, a soil inhabitant. Infection in both humans and animals is acquired by the inhalation of fungus-laden dust particles or, rarely, through a primary infection of the skin. The severity of coccidioidomycosis can range from very mild, simulating a common cold, to an acute disseminated fatal disease, especially in patients with AIDS. An allergic reaction with erythema multiforme or erythema nodosum occurs in some cases. The basic symptoms of malaise and fever may suggest coccidioidomycosis if the patient has traveled through an endemic area. Diagnosis is made by KOH mounts of sputum or isolation of the fungus in a culture. Colonies of the coccidioidomycosis fast-growing phase are dangerous to handle, and the greatest care should be implemented while manipulating cultures. Treatment includes amphotericin B, ketoconazole, and itraconazole.
CHROMOBLASTOMYCOSIS. (Fig 35-16. and Fig 35-17). Chromoblastomycosis is a chronic cutaneous mycosis, characterized by a distinct clinical presentation and the presence of the so-called sclerotic bodies on tissue cuts. A great variety of fungi are able to cause the disease, including Phialophora verrucosa, Fonsecaea pedrosoi, Fonsecaea compacta, Cladosporium carrionii, Rhinocladiella aquaspersa, and Botryomyces caespitosus. The disease has been reported worldwide, with most cases coming from the tropical and subtropical areas of South America and Africa. Some fungi have a preference for certain climates. Fonsecaea pedrosoi is most common in wet and humid areas within the torrid zones, whereas C. carrionii prefers dry and semidesert regions of the tropical-intertropical zones. The most commonly affected areas are the lower extremities, although in some arid geographic locations such as Venezuela, the upper girdle (shoulder, arm, back) is the prevalent site of infection. The primary process occurs at the site of inoculation, most probably through traumatized skin. The fungus is acquired from the environment, where it lives as saprophytes of wood, vegetable debris, or soil. The disease is not transmitted from person to person. The primary lesion is exophytic and either a papule, a nodule, or a tumor. The lesions multiply and tend to coalesce, forming plaques with a verrucous surface. Ulceration may develop, but there is no fistula formation, as in mycetoma, and the bone and muscle are spared. The affected limbs may end up in elephantiasis. The diagnosis is easily made by direct examination with KOH of scrapings from the lesion. The morphology adopted by the fungus is a cluster of oblong round cells with thick walls and flattened abutting surface, divided by septation in more that one plane, and is known as sclerotic bodies or muriform cells. The histopathology shows pseudocarcinomatous hyperplasia with a granulomatous suppurative reaction in the dermis. The sclerotic bodies have a brown color and are easily identified by their size (4 to 12 microns) and look like copper pennies. Species identification is only possible after culture isolation on Sabouraud media for 4 to 6 weeks. Treatment options include surgical excision when the lesion is small. Pharmacologic agents that are reported to be useful, but probably not curative by themselves, include 5-flucytosine, itraconazole, and saperconazole.
MYCETOMA OR MADUROMYCOSIS. (Fig 35-18). This disease is caused by at least 20 different fungi and actinomyces. The organisms gain entry into the body by trauma. It is more common in adult males who work outdoors barefoot or who expose large areas of the skin, as would stevedores. The clinical picture manifests over 10 or 15 years as nodules that later evolve into edematous areas with even larger nodules, and fistula that drain or expel "grains." Black grains are usually due to fungi, and red grains are usually due to actinomyces. Final diagnosis requires a culture study and treatment depends on the organism isolated.
SPOROTRICHOSIS. (see Chap 19). Sporotri-chosis (Fig.^35-19; see Fig 19-16) is a mycotic infection produced by the environmental fungus, Sporothrix schenckii. It has worldwide distribution, although endemic areas do exist, for example, in the Peruvian Andes. It is commonly associated with trauma from rose thorns and is an occupational hazard for florists and gardeners. The classical picture (about 70% of the cases) is the so-called lymphocutaneous or sporotricoid pattern characterized by primary lesion, mostly an ulcerated plaque, followed by several satellite lesions either papular, nodular, or crusted, in a linear lymphatic distribution. It is commonly located on an extremity. There is a second type of presentation with only one isolated lesion as either a plaque, a nodule, or an ulcer. This is known as the fixed cutaneous form of sporotrichosis. Rarely, the infection can disseminate to involve multiple sites and organs. On histology, the findings are those of a granulomatous reaction, often with a suppurative component. The fungus is rarely seen on direct examination or on tissue cuts even with special stains. When visible, it has a levaduriform morphology. Fortunately, the fungus grows easily on Sabouraud media, which is the most reliable way to make the diagnosis. The intradermal reaction known as the sporotriquin test is also of great help to exclude the diagnosis. Treatment options include the use of potassium iodide solution and itraconazole, both given for a period of four weeks after achieving total remission.
PARACOCCIDIOIDOMYCOSIS, (Fig 35-20). As opposed to sporotrichosis and chromoblastomycosis, in which the disease is located at the inoculation site, paracoccidioidomycosis is a systemic disease with hematogenous spreading from a primary pulmonary focus. The infection has a specific geographic distribution through Central and South America. In some countries, such as Brazil, it reaches the status of a public health problem. The agent, Paracoccidioides brasiliensis, is a dimorphic fungus with special preference for tropical and subtropical forests with mild temperatures and high humidity. The infection is acquired by inhalation, with a primary lesion in the lung. From there it may take two courses: one is an aggressive form with an acute severe pneumonia and rapidly progressive systemic disease; the second form has a relentless course with chronic pulmonary disease. The typical patient is a middle-aged male agricultural worker. They may present themselves to the dermatologist with involvement of the mucosae and skin. The lesions on lips, buccal mucosae, gums, palate, and pharynx are infiltrating ulcerated plaques and nodules with subsequent destruction and scarring deformities of those structures. On the skin the lesions vary widely. They may begin as small acneiform pustules 2 to 3 mm in size that later ulcerate, or they can adopt a pattern related to affected lymph nodes. Cold abscess may develop and in some instances multiple symmetric papules with verrucous surfaces may be present on the soles, easily misinterpreted as warts. The size of the fungus and its characteristic morphology allows easy identification on sputum preparations and scraping from the mucosa and cutaneous lesions. It is easy to recognize the yeast with multiple gemmations, giving the "pilot wheel" appearance. Identical structures are seen on histologic examination of the affected tissues. The reaction pattern seen on biopsy is a granulomatous reaction with multiple giant cells, some of them engulfing the budding elements. The fungus grows on Sabouraud medium in 4 or more weeks, as a mold at 20 to 26°C and as a yeast at 34 to 37°C. Treatment choices have evolved from sulfonamides to ketoconazole up to the new triazoles (itraconazole and fluconazole). At present, itraconazole is considered the drug of choice because of the lower doses required, shorter period of treatment, and fewer side effects.
LOBOMYCOSIS. (Fig 35-21).This chronic skin infection is produced by Loboa loboi, a large fungus with levaduriform morphology. The disease is endemic in rural areas of the Brazilian Amazon. The same organism is able to cause disease in dolphins in North America and Europe. The condition is acquired by primary inoculation from the environment through traumatized skin. The clinical lesions take years to develop. The classic clinical manifestation is the formation of nodules with a keloid appearance usually located on extremities, ears, face, and neck, with the scalp being spared in most cases. Other elementary lesions include infiltrated plaques, gummas, ulcers, and varicoid nodules. The histology consists of a massive histiocytic infiltrate without the pseudocarcinomatous hyperplasia commonly seen in chromoblastomycosis. This explains why in lobomycosis the nodules tend to have a smooth surface, as opposed to the verrucous surface of chromomycosis. The morphology of the fungus is quite distinctive, with globose, lemon-shaped buds 9 to 10 meters in diameter organized in short and long chains of uniform beads. The organism is easily seen in KOH preparations from lesions. The fungus has not been grown in culture media. The only effective treatment is wide surgical excision. Recurrence is very common.
Figure 35-21. Lobomycosis. Note the smooth surface and compare to chromoblastomycosis (Fig. 35-17).
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Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.