|The Center had developed many new diagnostic tools for Mycetoma diagnosis|
Fine Needle Aspiration Cytology of Mycetoma:
Mycetoma can be accurately diagnosed by Fine Needle Aspiration (FNA) cytology. Mycetoma lesion has a distinct appearance in a cytological smear characterised by the presence of polymorphous inflammatory cells consisting of an admixture of neutrophils, lymphocytes, plasma cells, histiocytes, macrophages and foreign body giant cells and grains. In sections, the grain is closely surrounded by and occasionally infiltrated by neutrophils causing its fragmentation. Outside the neutrophil zone, monocytic cells and giant cells are seen. Thisis surrounded by granulation tissue rich in fibroblasts and blood vessels. FNA cytology allows morphological identification of mycetoma and its classification into eumycetoma and actinomycetoma; this is important as the treatment depends mainly on the aetiological agents.
The technique is simple, cheap, rapid, sensitive and can be tolerated by patients. It can be used not only in routine diagnosis but can be used as an effective mean in the collection of material for culture and immunological studies. Due to the simplicity of the technique, it can be used in epidemiological survey of mycetoma and for detection of early cases in which the radiological and serological techniques may not be helpful.
EL Hag IA, Fahal AH, Khali EAG, Fine needle aspiration cytology of mycetoma. Acta Cytologica. 1996; 40(3): 461-464.
Yousif BM, Fahal AH, Yahia MY. The Cell Block Technique: A New Diagnostic Tool for Mycetoma. Trans R Soc Trop Med Hyg. 2010; 104(1):6-9.
Ultrasonic imaging of mycetoma:
The mycetoma grains, its capsule and the accompanying inflammatory granuloma have characteristic ultrasonic appearances. Ultrasound imaging can differentiate between eumycetoma and actinomycetoma and between mycetoma and other non-mycetoma lesions. In eumycetoma lesions, the grains produce numeroussharp, bright hyperreflective echoes, which are consistent with the black grains. The grain cement substance is most probably the origin of these sharp echoes. Also, there are multiple thick-walled cavities with absent acoustic enhancement. In actinomycetoma lesion the findings are similar, but the grains are less distinct. Thismaybe due to their smaller size and consistency, individual embedding of the grains or the absence of the cement substances in few of them.
The ultrasonic diagnosis of mycetoma is more precise and accurate in lesions with no sinuses. The size and extent of the lesion can be accurately determined ultrasonically, and this is useful in planning surgical incisions and procedures.
Fahal AH, Sheikh HE, EL Lider MA, Homeida MA, EL Arabi YE, Mahgoub ES, Ultrasonic imaging in mycetoma. BriJSurg. 1997; 78: 765-766.
Magnetic Resonance Imaging of Mycetoma:
MRI is a non-invasive imaging, it can characterise the soft tissue masses of mycetoma and aid in early diagnosis. In mycetoma, the MRI appearance is in the form of the dot-in-circle sign which is aunique pathological feature of mycetomaand it is highly specific sign for mycetoma. In advanced cases, MRI is essential to plan the treatment options.
EL Shamy, ME, Fahal AH, Shakir MY, Homedia MMA. New MRI Grading System for the Diagnosis and Management of Mycetoma. Trans R Soc Trop Med Hyg. 2012; 106(12):738-42.
Molecular Identification of Mycetoma Causative Organisms:
Most of the fungi that cause mycetoma grow slowly and culture plates should be incubated for at least four weeks before being discarded as negative. Identification of the isolated fungus is based on thegross morphology of fruit bodies and conidia, if present. Conventional mycological identification is difficult in some species such as T. grisea, Madurella mycetomatis, Neotestudina rosatii, Pyrenochaeta mackinnonii, and Pyrenochaeta romeroi. Most of these species donot sporulate readily, and identification is based on molecular techniques, particularly sequencing of the rDNA Internal Transcribed Spacer (ITS) region.
The molecular diagnosis of a number of eumycetoma causing agents has been developed. The black yeast Exophiala jeanselmei and Phaeoacremonium are recognisable by sequence data of the rDNA Internal Transcribed Spacer (ITS) region. SEQ CHAPTER \h \r 1rDNA Restriction Fragment Length Polymorphism and specific ITS-PCR were used for species identification of Madurella mycetomatis. Although Scedosporium apiospermum cultures can be identified by culture morphology, PCR-based assays for rapid diagnosis of infections from infected tissue was found useful.
Ahmed SA, van de Sande WW, Desnos-Ollivier M, Fahal AH, Mhmoud NA, de Hoog GS. Application of Isothermal Amplification Techniques for the Identification of Madurella mycetomatis, the Prevalent Agent of Human Mycetoma. J Clin Microbiol. 2015 Aug 5. pii: JCM.01544-15.
Ahmed AO, Mukhtar MM, Kools-Sijmons M, Fahal AH, de Hoog S, van den Ende BG, Zijstara, ED, Verburgh H, Abugroun ESA, EL Hassan AM, van Beklkum A. Development of a species-specific PCR RFLP procedure for the identification of Madurella mycetomatis. J Clin Microbiol. 1999; 37(10):3175-8.