Page 179 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 6-4 Infectious Diseases
COCCIDIOIDOMYCOSIS
Saprophytic phase Parasitic phase
Sputum or
Coccidioidomycosis, or valley fever, is endemic in the discharged pus
southwestern United States. Patients who breathe in
spores (arthroconidia) from the fungus Coccidioides
immitis may become infected. Most patients do not
develop active disease; instead, their exposure is
confirmed by the presence of a positive delayed hyper- Mycelia
sensitivity test to the fungus. Primary cutaneous coc- Endospores
cidioidomycosis is a rare entity caused by inoculation discharged
of the fungus directly into the skin. By far the most
common form of cutaneous coccidioidomycosis is
caused by dissemination to the skin from a primary Septate hyphae
pulmonary infection.
Clinical Findings: This infection has a slightly Spherule with
increased incidence in African Americans. The Filipino endospores (seen
population appears to be at greatest risk for developing in sputum or pus)
severe disease. Males and females are equally affected. Arthrospores Characteristic granuloma
Most individuals who inhale the spores do not develop of nasolabial fold
active disease. Rather, the fungus lies dormant or
trapped within pulmonary granulomas. About one third
of patients who are exposed to the fungus develop an Inhalation or skin penetration
acute pneumonitis. Fever, cough, malaise, and pleurisy
are the main symptoms. The pneumonitis may be
severe enough to bring the patient to the clinic to seek
therapy, but many cases are mild and patients routinely
dismiss them as the common cold. Reactivation later in
life may occur secondary to acquired immunosuppres-
sion, pregnancy, or older age.
Cutaneous findings in coccidioidomycosis have a
variable morphology. Papules, plaques, and nodules are
the most frequent forms of disseminated coccidioido-
mycosis. These skin lesions have a predilection to affect
the face, and in particular the nasolabial skin fold. Mul-
tiple draining cutaneous abscesses with fistula and sinus
formation can occur in late untreated disease. Chronic
ulcerations have also been reported to be a manifesta-
tion of cutaneous disease.
Nonspecific skin findings attributed to fungal infec-
tion with C. immitis are well recognized. The best Mycelial phase of C. immitis in culture
reported and most clearly associated finding is erythema on Sabouraud’s medium; highly
nodosum. Erythema nodosum is a reaction that occurs infectious
in many internal and cutaneous disease states. Almost
any deep fungal infection can induce erythema nodosum.
Patients who have a history of travel to an endemic area
should be screened for this fungal disease. Rarely, ery-
thema multiforme and Sweet’s syndrome have been
reported in association with coccidioidomycosis. Multiple draining sinuses
Pulmonary disease is almost always present and and ulcerated plaques
should be thoroughly searched for in patients present-
ing with cutaneous coccidioidomycosis. Chest radio-
graphs may show many findings, including cavitary
lesions, hilar adenopathy, pneumonitis, pleural effu-
sions, and lobar disease. Occasionally to bones,
The only method to make a diagnosis is with an liver, or spleen
appropriate tissue culture that shows growth of the
causative fungus. The clinical examination and history
are not as sensitive or specific as culture of the fungus. Meningitis with hydrocephalus;
If one has a high index of suspicion for this disease, uncommon but often fatal
treatment should be instituted and then adjusted after
the culture results become available. Pathogenesis: Coccidioidomycosis is caused by the readily converts back to its mycelial phase and can
Histology: Punch biopsy or excisional biopsy speci- soil-dwelling fungus, C. immitis. Endemic to the south- infect another host.
mens show a diffuse granulomatous inflammatory infil- western United States, Central America, and parts of Treatment: The azole antifungals fluconazole and
trate. Pseudocarcinomatous epithelial hyperplasia often South America, this fungus is found in the environment itraconazole are first-line therapies for coccidioidomy-
overlies the granulomatous infiltrate. Within the gran- in its mycelial or mold phase. It produces white, light, cosis. Treatment typically lasts 6 to 12 months; pro-
ulomatous portion of the dermal infiltrate are the and fluffy arthrospores. These arthrospores are highly longed therapy may be required in some cases. Severe,
characteristic spherules that contain endospores. The infectious. Once inhaled, this dimorphic fungus turns life-threatening cases and those refractory to azole anti-
spherules are thick walled and can readily be seen on into its yeast form. The yeast form is made of thick- fungal medications are usually treated with amphoteri-
specimens routinely stained with hematoxylin and eosin walled spherules with multiple, centrally located endo- cin B. Adjunctive surgical treatment can be used to
stain. The spherule can be highlighted with the use of spores that can be released from the host by coughing debride abscesses and remove isolated pulmonary
a silver stain. or by drainage of an abscess. The resulting endospore disease.

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