COCCIDIOIDOMYCOSIS
Coccidioidomycosis, or valley fever, is endemic in the 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-sensitivity test to the fungus. Primary cutaneous coccidioidomycosis is a rare entity caused by inoculation 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 pulmonary infection.
Clinical Findings: This infection has a slightly increased incidence in African Americans.
The Filipino population appears to be at greatest risk for developing severe
disease. Males and females are equally affected. Most individuals who inhale
the spores do not develop 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 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 immunosuppression, pregnancy, or older age.
Cutaneous findings in coccidioidomycosis have a
variable morphology. Papules, plaques, and nodules are the most frequent forms
of disseminated coccidioidomycosis. These skin lesions have a predilection to
affect the face, and in particular the nasolabial skin fold. Multiple draining
cutaneous abscesses with fistula and sinus formation can occur in late
untreated disease. Chronic ulcerations have also been reported to be a
manifestation of cutaneous disease.
Nonspecific skin findings attributed to fungal
infection with C. immitis are well recognized. The best reported and
most clearly associated finding is erythema nodosum. Erythema nodosum is a
reaction that occurs 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, erythema multiforme and Sweet’s syndrome have been reported in
association with coccidioidomycosis.
Pulmonary disease is almost always present and should
be thoroughly searched for in patients presenting with cutaneous
coccidioidomycosis. Chest radiographs may show many findings, including
cavitary lesions, hilar adenopathy, pneumonitis, pleural effusions, and lobar
disease.
The only method to make a diagnosis is with an
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. If one has a high index of suspicion for this disease, treatment
should be instituted and then adjusted after the culture results become
available.
Histology: Punch biopsy
or excisional biopsy specimens show a diffuse granulomatous inflammatory
infiltrate. Pseudocarcinomatous epithelial hyperplasia often overlies the
granulomatous infiltrate. Within the granulomatous portion of the dermal
infiltrate are the characteristic spherules that contain endospores. The
spherules are thick walled and can readily be seen on specimens routinely
stained with hematoxylin and eosin stain. The spherule can be highlighted with
the use of a silver
stain.
Pathogenesis: Coccidioidomycosis is caused by the soil-dwelling fungus, C. immitis. Endemic to the south-western United States, Central America, and parts of South America, this fungus is found in the environment in its mycelial or mold phase. It produces white, light, and fluffy arthrospores. These arthrospores are highly infectious. Once inhaled, this dimorphic fungus turns into its yeast form. The yeast form is made of thick-walled spherules with multiple, centrally located endospores that can be released from the host by coughing or by drainage of an abscess. The resulting endospore readily converts back to its mycelial phase and can infect another host.
Treatment: The azole
antifungals fluconazole and itraconazole are first-line therapies for
coccidioidomycosis. Treatment typically lasts 6 to 12 months; prolonged
therapy may be required in some cases. Severe, life-threatening cases and those
refractory to azole anti-fungal medications are usually treated with
amphotericin B. Adjunctive surgical treatment can be used to debride abscesses
and remove isolated pulmonary disease.
