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Respiratory tract intracavitary colonization due to Scedosporium apiospermum: report of four cases

Colonização intracavitária do trato respiratório por Scedosporium apiospermum: relato de quatro casos

Abstracts

Four cases of respiratory tract intracavitary colonization (fungus ball) due to Scedosporium apiospermum (teleomorph, Pseudallescheria boydii) are reported. The need for a careful search for anneloconidia, in order to establish the etiologic diagnosis in the clinical specimen by microscopy, is emphasized.

Scedosporium apiospermum; Scedosporiosis; Pseudallescheria boydii; Pseudallescheriosis; Respiratory intracavitary colonization; Fungus ball


São relatados quatro casos de colonização intracavitária (bola fúngica) do trato respiratório por Scedosporium apiospermum (teleomorfo, Pseudallescheria boydii). É enfatizada a necessidade de cuidadosa busca de aneloconídios, a fim de estabelecer o diagnóstico etiológico no espécime clínico, através da microscopia.


CASE REPORT

Respiratory tract intracavitary colonization due to Scedosporium apiospermum. Report of four cases

Colonização intracavitária do trato respiratório por Scedosporium apiospermum. Relato de quatro casos

Luiz Carlos SeveroI; Flávio de Mattos OliveiraII; Klaus IrionIII

IPesquisador 1c CNPq; Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil

IILaboratório de Micologia Clínica, Santa Casa - Complexo Hospitalar, Porto Alegre, RS, Brasil

IIIPavilhão Pereira Filho, Santa Casa - Complexo Hospitalar, Porto Alegre, RS, Brasil

Correspondence Correspondence to Dr. Luiz Carlos Severo Laboratório de Micologia Clínica, Santa Casa - Complexo Hospitalar, Annes Dias 285, 90020-090 Porto Alegre, RS, Brasil Fax: (55) 51 3214-8435 Email: severo@santacasa.tche.br

SUMMARY

Four cases of respiratory tract intracavitary colonization (fungus ball) due to Scedosporium apiospermum (teleomorph, Pseudallescheria boydii) are reported. The need for a careful search for anneloconidia, in order to establish the etiologic diagnosis in the clinical specimen by microscopy, is emphasized.

Keywords: Scedosporium apiospermum; Scedosporiosis; Pseudallescheria boydii; Pseudallescheriosis; Respiratory intracavitary colonization; Fungus ball.

RESUMO

São relatados quatro casos de colonização intracavitária (bola fúngica) do trato respiratório por Scedosporium apiospermum (teleomorfo, Pseudallescheria boydii). É enfatizada a necessidade de cuidadosa busca de aneloconídios, a fim de estabelecer o diagnóstico etiológico no espécime clínico, através da microscopia.

INTRODUCTION

Scedosporium apiospermum is classified as an ascomycetes; the homothallic teleomorph state is called Pseudallescheria boydii, previously named as Allescheria and Petriellidium. This fungus is ubiquitously found worldwide, occurring in nutrient-rich, poorly aerated environment, such as polluted water3.

The spectrum of disease in the respiratory tract is similar in terms of variety and severity to those caused by Aspergillus2. Differential diagnosis1 is mandatory because of the frequent resistance of the Scedosporium to a variety of commonly used antimycotic agents6.

The noninvasive, colonization infection by S. apiospermum in a preformed10 or natural14 air space has been named in the literature as mycetoma13,15, fungoma7, fungus ball8,10, non-aspergillus aspergilloma5, and pseudallescherioma9. Mycetoma is recognized by tumefaction and draining sinuses, diagnosed by granules. Almost all cases of S. apiospermum infection are eumycotic white-grain mycetoma12. Fungus ball consists of a mass of hyphal colonizing a cavity. The suffix "oma" must be restricted to fungal pulmonary nodule11. An additional confusion arose from the SCHWARTZ12 publication of a lung sequestrum by S. apiospermum termed fungoma (fungus ball). It is preferable to use intracavitary colonization because it encompasses the initial fungal growth or the true fungus ball5.

In this report, we describe four cases of S. apiospermun pulmonary intracavitary colonization (fungus ball) emphasizing the need for a careful search for hystological demonstration of conidia, specially in cases without culture and in absence of Aspergillus conidial heads, because some cases of scedosporiosis were mistakenly diagnosed on histologic examination as aspergillosis.

CLINICAL CASES

Case 1: A 45 year-old, white carpenter presenting rheumatic arthritis had been receiving prednisone (20 mg/day) for 4 years. At admission he complained of bouts of hemoptysis during the last two years. A chest x-ray revealed a cystic lesion occupying the apex of the right lung, with various oval masses in the dependent portion of this cavity (Fig. 1). No precipitin bands were obtained in immunodiffusion (ID) test with Aspergillus fumigatus, A. niger, A. flavus and Scedosporium apiospermum antigens.


A lobectomy was performed. At cut section a post necrotic cavity, containing a dull greenish material was seen. Suppurative chronic inflammatory reaction, arterities and a partial coating composed of squamous metaplasic respiratory epithelium lined the cavitation. Suppurative chronic bronchopneumonia, bronchiectasis and interstitial fibrosis were also observed.

Histopathology: The intracavitary mass consisted of a network of hyaline, septate, branched hyphae and some oval conidia.

Mycology(cultures): Colonies of S. apiospermum were obtained in Sabouraud dextrose agar and incubated at 25 and 35 ºC.

No antifungal therapy was administered. No evidence of recurrence was observed in a follow-up of two years.

Case 2: This patient was a 36 year-old, white, diabetic woman. She complained of chest pain on the right side, fever, cough with purulent expectoration, and dyspnea initiated two years ago. She received penicillin for ten days without improvement. She was non reactor to Mantoux test and had no history of tuberculosis. Linear tomogram showed a nodular mass with meniscus sign, in the right lower lobe (4.5 x 3.5 cm) with undefined border and within an irregular cavitation. The cavity was connected to the axial bronchus without bronchial stenosis.

A subsegmentar resection was performed. At cut section a mass inside a post necrotic cavity was seen. The wall of the cavity was partially composed of respiratory epithelium and presented signs of chronic suppurative reaction.

Histopathology: The mass was composed of intermingled branched septate hyphae and some conidia.

Mycology(cultures):S. apiospermum was isolated in Sabouraud dextrose agar and incubated at 25 and 35 ºC.

The patient was successfully treated with surgery only.

Case 3: With a past history of tuberculosis, the patient, a 57 year-old white woman was admitted complaining of pain on the right side of the thorax and two bouts of hemoptysis in the previous three months. A chest roentgenogram showed partial fibroatelectasic retraction of the left upper lobe and a thin-walled cavity, which contained rounded opacity in its dependent portion (Fig. 2). Acid-fast bacilli were not detected in sputum examination; no precipipitin bands were observed in ID test with aspergillins.


A lobectomy of the left upper lobe was performed. A mass (16 g) was removed from a post necrotic cavitation (9.5 x 7.5 cm). This cavitation was lined with chronic suppurative inflammatory tissue and a palissade of granulomata. The nodules and micronodules were composed of tuberculoid granulomata with caseous necrosis. Some nodules were calcified.

Histopathology: Hyaline, septate, branching hyphae and conidia were seen in microscopic examination of the mass.

Mycology(cultures):S. apiospermum was isolated in culture in Sabouraud dextrose agar and incubated at 25 and 35 ºC, and later on, the appearance of cleistothecia led to the diagnosis of P. boydii.

One year after surgical treatment the patient was in good conditions.

Case 4: A 66-year-old, otherwise healthy man presented with chronic cough with purulent expectoration. He had an 8-year history of multiple antibiotic unsuccessful empirically treatments for various lengths of time.

A computed tomographic scan showed partial opacification of the left maxillary sinus along with thickening of the sinus mucosal with irregular soft tissue mass, with anfractuous contours, without calcifications and bone erosion (Fig. 3). The patient underwent to surgery that disclosed soft tissue mass occupying the left maxillary sinus.


Histopathology: The sinus content demonstrated dense conglomerated dichotomously branching septated hyphae with conidia of S. apiospermum. Hematoxylin and eosin-stained tissue showed mucosal chronic inflammation without tissue invasion.

Mycology(cultures): Fragments of the ball were cultured on Sabouraud dextrose agar and incubated at 25 and 35 ºC. Cultures were positive within a week, yielding colonies of P. boydii.

Surgical treatment resulted in complete recovery of the patient.

Histopathologic findings of the fungus ball: Tissue sections were prepared with fixation in 10% formalin and stained with hematoxilin-eosin (H&E) and Gomori's methenamine-silver (GMS). The diagnosis of fungal ball was made by the demonstration of mass of fungi consisting of compact hyphae characterized by concentric rings of growth with distorted, aberrant and bulbous central hyphal strands. The conidia produced in the inner part of the fungal growth (Fig. 4) and the chlamydospores in the periphery of the ball (Fig. 5) made the diagnosis of S. apiospermum and the cleistothecia observed in culture confirmed P. boydii (Fig. 6).




DISCUSSION

The definitive etiologic characterization of S. apiospermum respiratory tract intracavitary colonization requires recovery of the organism by culture from the cavity (Table 1). However, serum precipitins may be of aid in diagnosis10 and can be used as a screening test.

When cultural confirmation is not available, proof of the etiologic agent could be obtained by histopathologic examination. Fungus ball due to S. apiospermum, on haematoxylin and eosin stained sections, is primarily composed by tangled septate hyaline hyphae that is distinguished from Aspergillus by direct-immunofluorescence4.

Other microscopically distinctive features are the production of anneloconidia and chlamydospores in the fungus ball. Anneloconidia represents an actively growing element of the fungus deeply in the zonation of hyphal growth. The peripheral zone is composed of densely packed aggregation of large, thickwalled chlamydospores. Among these, one can observe an intermediate zone with both fungal elements. These findings raise the hypothesis that the chlamydospores constitute a phase of the anneloconidia that comes up in contact with an air space.

Finally, surgical removal of the fungus ball is the most successful method of treatment of respiratory tract intracavitary colonization by S. apiospermum as observed in our patients.

ACKNOWLEDGEMENTS

We wish to thank Dr. Leo Kaufman (CDC, Atlanta, GA, USA) for performing the immunodiffusion tests.

Received: 19 August 2003

Accepted: 23 December 2003

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  • Correspondence to
    Dr. Luiz Carlos Severo
    Laboratório de Micologia Clínica, Santa Casa - Complexo Hospitalar, Annes Dias 285, 90020-090 Porto Alegre, RS, Brasil
    Fax: (55) 51 3214-8435
    Email:
  • Publication Dates

    • Publication in this collection
      29 Mar 2004
    • Date of issue
      Feb 2004

    History

    • Accepted
      23 Dec 2003
    • Received
      19 Aug 2003
    Instituto de Medicina Tropical de São Paulo Av. Dr. Enéas de Carvalho Aguiar, 470, 05403-000 - São Paulo - SP - Brazil, Tel. +55 11 3061-7005 - São Paulo - SP - Brazil
    E-mail: revimtsp@usp.br