Section 3 -

Filamentous Fungi in Histologic Sections Mary Klassen-Fischer

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 Click to view with ImageScope Click to view with a Web-Based Viewer 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 Rhizopus species. 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 fungi Dermatophytes Filamentous Arthroconidia Fusarium species Filamentous Parallel contours, dichotomous right angle branching Histoplasma capsulatum Round Characteristic round to oval or collapsed forms with narrow-necked budding, vacuole, small dot 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, characteristic conidia Pythium insidosum Filamentous Width up to 10 m, branching, infrequent septation 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 characteristic sporangia References 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.