Histopathology and Mycology of Fungal Infections
Moderators: Michel Huerre, Gary W. Procop, Mary Klassen-Fischer, Randall T. Hayden, Glenn D. Roberts
Section 3 -
Filamentous Fungi in Histologic Sections
Case 3 - Clinical History
The patient was a 61 year old white male from Texas admitted to the hospital from the diabetic clinic
with complaints of malaise for one month, anorexia and weight loss of approximately 16 kg (35 pounds)
occurring over the past year, but most pronounced over the past 2 months. Three weeks prior to
admission, he had a few episodes of nausea and vomiting. Two weeks prior to admission, he developed
right pleuritic chest pain, non-productive cough, afternoon fevers to 38.5 ºC (101º F) and chills but no
night sweats or hemoptysis.
Case 3 - Figure 1
His preexisting medical conditions included adult onset diabetes, cholelithiasis, chronic alcoholic
pancreatitis, transitional cell cancer of the bladder for 13 years, emphysema for 23 years and arthritis.
He had malaria 43 years ago. His past surgical history included distal pancreatectomy,
pancreaticojejunostomy, Roux-en-Y and splenectomy performed 6 years prior and transurethral resections of
bladder tumors performed 8 times, most recently two years prior. He drank 3 to 4 beers per day. He had
smoked 2 packs per day for 10 years but switched to pipe smoking in the past 7 or 8 years. He had
shortness of breath after 3 to 4 blocks of walking. His only medication was aspirin.
Chest X-ray revealed an extensive cavitary infiltrate involving the right upper lobe and possibly the
right middle lobe. Plasma glucose was 16.8 mmol/L (302 mg/dl), serum creatinine 99 mmol/L (1.3 mg/dl),
hemoglobin 111 g/L (11.1 g/dl), and hematocrit 0.33 (33.1%). Endobronchial biopsy of the right upper
lobe revealed hyphal elements, and amphotericin treatment was begun in anticipation of surgical
resection. The patient subsequently developed massive hemoptysis leading to cyanosis, apnea and asystole
that was not able to be converted with defibrillation.
Autopsy showed pleural effusions and marked bilateral pleura adhesions that were more extensive over
the right upper lobe. There were focal areas of consolidation and marked congestion throughout both
lungs. Upon dissection, the right upper lobe was found to contain massive caseous necrosis with areas of
hemorrhage. The bronchial tree was filled with red blood bilaterally that appeared to be emanating from
the right upper lobe. The left upper lobe revealed severe bullous panacinar emphysema. The stomach
contained 1 liter of undigested blood. Other autopsy findings included fibrinous pericarditis, right
ventricular and atrial dilatation, pancreatic fibrosis, acute and chronic hepatic congestion, hepatic
fatty metamorphosis, and urinary bladder dilatation without mucosal abnormalities.
Bacteriologic cultures of lung were positive for Klebsiella pneumoniae
and Streptococcus viridans. Blood cultures were positive for Klebsiella pneumoniae. Cultures from the endobronchial biopsy were positive for
Filamentous Microorganisms in Histologic Sections
|Microorganism ||Predominant forms in tissue ||Distinguishing features|
|Actinomyces species ||Filamentous ||Width up to 1 m, gram-positive|
|Aspergillus species ||Filamentous ||Parallel contours, dichotomous acute angle |
branching, characteristic conidia
|Candida species||Round and Filamentous ||Pseudohyphae, gram-positive|
|Coccidioides species ||Round ||Characteristic spherules with endospores|
|Cryptococcus neoformans ||Round ||Characteristic pleomorphic yeast-like forms |
with narrow-necked budding, mucicarmine
and Fontana positive
|Dematiaceous ||Filamentous ||Pleomorphic, some pigmented|
|Dermatophytes ||Filamentous ||Arthroconidia|
|Fusarium species ||Filamentous ||Parallel contours, dichotomous right angle |
|Histoplasma capsulatum ||Round ||Characteristic round to oval or collapsed|
forms with narrow-necked budding, vacuole,
|Malassezia furfur ||Round and Filamentous ||Characteristic yeast-like forms with small buds|
|Nocardia species ||Filamentous ||Width up to 1 m, gram-positive, weakly acid-fast|
|Pseudallescheria boydii ||Filamentous ||Parallel contours, haphazard branching,|
|Pythium insidosum ||Filamentous ||Width up to 10 m, branching, infrequent|
|Trichosporon species ||Round and Filamentous ||Irregular contours, haphazard branching, |
pleomorphic yeast-like cells, rectangular arthroconidia
|Zygomycetes ||Filamentous ||Width up to 20 m, irregular contours|
haphazard branching, infrequent septation
- Chandler FW, Watts JC. Pathologic Diagnosis of Fungal Infections. Chicago: ASCP Press, 1987.
- Kwon-Chung KJ, Bennett JE. Medical Mycology. Philadelphia: Lea & Febiger, 1992.
- Walsh TJ, Rex JH. Fungal infections, part I: recent advances in diagnosis, treatment, and prevention of opportunistic mycoses. Infect Dis Clin North Am 16(4):Dec 2002.
- Walsh TJ, Rex JH. Fungal infections, part II: recent advances in diagnosis, treatment, and prevention of endemic and cutaneous mycoses. Infect Dis Clin North Am 17(1):Mar 2003.