Mycetoma: comparison of MR imaging with CT

Mycetoma imaging: the best practice

Mycetoma is a recognised neglected tropical disease that for a long time has been accorded inadequate attention across the globe. It is a chronic destructive inflammatory disease caused by fungi (eumycetoma) or actinomycetes (actinomycetoma). Mycetoma treatment depends on an accurate and precise diagnosis. The cornerstone for proper disease diagnosis is identification of the causative organisms, but also critical for diagnosis and management planning is determination of its extent along and across tissue planes. An initial diagnosis is made after clinical assessment. Clinical examination alone does not identify the causative organism nor does it detect the spread of disease along the different tissue planes and bone. Imaging techniques, such as radiography, ultrasonography, computed tomography scan and magnetic resonance imaging can be used to determine the extent of lesions. In this communication, the Mycetoma Research Centre, World Health Organization Collaborating Centre on Mycetoma, University of Khartoum, presents its experience and recommendations on mycetoma diagnostic imaging.

Differentiation between infectious spondylodiscitis versus inflammatory or degenerative spinal changes: How can magnetic resonance imaging help the clinician?

Spondylodiscitis is a complex disease whose diagnosis and management are still challenging. The differentiation between infectious and non-infectious aetiology is mandatory to avoid delays in the treatment of life-threatening infectious conditions. Imaging methods, in particular magnetic resonance imaging (MRI), play a key role in differential diagnosis. MRI provides detailed anatomical information, especially regarding the epidural space and spinal cord, and may allow differential diagnosis by assessing the characteristics of certain infectious and inflammatory/degenerative lesions. In this article, we provide an overview of the radiological characteristics and differentiating features of non-infectious inflammatory spinal disorders and infectious spondylodiscitis, focussing on MRI results and presenting relevant clinical and pathological features that help early diagnosis.

Eumycetoma: A Perspective for Military Primary Care

This is a case report of a 42-year-old woman who presented to a clinic with a history of progressive left foot and ankle swelling. She had a suspected history of myectoma, but had never been officially diagnosed despite repeated cultures and debridements over the course of decades. The inciting event occurred approximately 30 years prior in her home country of Belize. Her wound culture revealed Scedosporium apiospermum as the causative agent. Treatment included surgical debridement and oral antifungal therapy. This case represents an interesting adjunct to the differential diagnosis for military physicians, as mycetomas are prevalent in many of the areas where our forces are deployed and may only present after the service member has left active service because of its naturally indolent course.

Soft tissue mycetoma: "Dot-in-circle" sign on magnetic resonance imaging

A 36-year-old Mexican female with a slowly growing foot mass was referred to orthopedic surgery clinic for further evaluation. Foot magnetic resonance imaging revealed an infiltrative soft tissue mass along the dorsal aspect of the fourth metatarsal. T2-weighted images revealed multiple central low-signal “dots” surrounded by areas of bright signal intensity, known as the “dot-in-circle” sign, which is highly specific for mycetoma. Surgical biopsy confirmed the diagnosis of bacterial mycetoma in this patient. Mycetoma can lead to progressive deformity and loss of function, as well as possible limb amputation in the case of delayed diagnosis or misdiagnosis. The “dot-in-circle” sign on magnetic resonance imaging can assist in rendering a final diagnosis and distinguish mycetoma from other etiologies of a soft tissue mass, such as a sarcoma or benign soft tissue lesions.

Reconstructive Surgery for Mycetoma: Is There a Need to Establish an Algorithm?

Background:

Mycetoma is a chronic, progressive, disfiguring, and destructive disease. It caused by a variety of microorganisms including fungi and higher bacteria. It is primarily an infection of the skin and soft tissue, most frequently affecting the lower extremity and the hand and spread through fascial planes and lymphatics.

Methods:

Current medical and surgical management are still inadequate and the recurrence rate is high with severe disabilities.

Results:

This review describes some reconstructive techniques that were performed to address essential aspects with regard to mycetoma surgical management that include coverage of large skin and soft-tissue defects left after local excisions, enhancing the rate of chronic mycetoma wound healing, and preservation or restoration of functional status of the affected limbs.

Conclusion:

These applied techniques—which had acceptable preliminary outcome—have to be considered by the surgeons dealing with mycetoma to improve the functional and cosmetic outcomes and to minimize tremendous morbidities and disabilities that are associated with this neglected disease.

Case 249: Intramuscular Mycetoma

History A 21-year-old man presented with swelling of the medial aspect of the left thigh of 1-month duration. There was no history of fever or penetrating injury in the left thigh. The patient had undergone renal transplantation 7 years earlier and had been taking immunosuppressants since transplantation. He had undergone two surgeries at the same site in the medial aspect of the left thigh in the past 3 years for a similar problem. At physical examination, there was swelling in the medial aspect of the left thigh, with mild tenderness. A surgical scar was noted anterior to the swelling ( Fig 1 ). No redness or discharging sinus was present. Laboratory results were as follows: hemoglobin level, 11.3 g/dL (normal range, 13.8-17.2 g/dL); white blood cell count, 9.7 × 10⁹/L (normal range, [4-11] × 10⁹/L); neutrophil, 75% (normal range, 48%-77%); lymphocyte, 22% (normal range, 10%-24%); eosinophil, 1% (normal range, 0.3%- 7%); monocyte, 1% (normal range, 0.6%-10%); serum creatinine level, 1.3 mg/dL (114.9 μmol/L) (normal range, 0.5-1.6 mg/dL [44.2-141.4 μmol/L]); and serum glucose (random) level, 82 mg/dL (4.5 mmol/L) (normal range, 79-140 mg/dL [4.4-7.8 mmol/L]). Radiography of the left thigh showed soft-tissue swelling in the medial aspect of the left thigh, without underlying bone involvement (not shown). Ultrasonography (US) and magnetic resonance (MR) imaging of the left thigh were performed. [Figure: see text].

The "dot-in-circle" sign in musculoskeletal mycetoma on magnetic resonance imaging and ultrasonography

This study aimed to present the ‘dot-in-circle’ sign, which indicates the typical magnetic resonance imaging (MRI) and ultrasonographic (USG) findings for mycetoma involving soft tissue and bone. A total of 8 cases with histopathological proof of mycetoma affecting the musculoskeletal system, and that were examined via MRI and/or coexistent diagnostic ultrasonography between 2004 and 2013 in Songklanagarind Hospital were included in this study. The ‘dot-in-circle’ sign on the MRI and USG images of all the patients was reviewed by two radiologists. The analytic method was descriptive. All cases of musculoskeletal mycetoma revealed the ‘dot-in-circle’ sign on MRI, which was seen as multiple, small, round- to oval-shaped hyperintense lesions separated and surrounded by a low-signal intensity rim (circle), and a tiny, central, low-signal focus (dot). An USG study was available in four patients, and all USG findings demonstrated the ‘dot-in-circle’ sign as a central hyperechoic area (dot) surrounded by hypoechoic tissue (circle). In conclusion, the ‘dot-in-circle’ sign is a typical feature on MRI and USG findings for the diagnosis of musculoskeletal mycetoma.

Madura foot: two case reports, review of the literature, and new developments with clinical correlation

"Madura foot" or pedal mycetoma is a rare destructive infection of the skin and subcutaneous tissues of the foot, progressing to involve muscle and bone. The infection can be caused by both bacteria and fungi. Infection typically follows traumatic implantation of bacteria or fungal spores, which are present in soil or on plant material. Clinically, this entity can be difficult to diagnose and can have an indolent and progressive course. Early diagnosis is important to prevent patient morbidity and mortality. We present two cases of pedal mycetoma, review the literature, review new developments in diagnosis, and discuss magnetic resonance imaging (MRI) features of this unusual entity.

Subcutaneous fungal infections

Subcutaneous mycoses are common in tropical and subtropical regions of the world. These infections have multiple features in common, including similar epidemiology, mode of transmission, indolent chronic presentation with low potential for dissemination in immunocompetent hosts, and pyogranulomatous lesions on histopathology. Herein, we provide up-to-date epidemiologic, clinical, diagnostic, and therapeutic data for three important subcutaneous mycoses: chromoblastomycosis, mycetoma, and sporotrichosis.

The Madura Foot

“Mycetoma” means a fungal tumor. Mycetoma is a chronic, granulomatous, subcutaneous tissue infection caused by both bacteria (actinomycetoma) and fungi (eumycetoma). This chronic infection was termed Madura foot and eventually mycetoma, owing to its etiology. Inoculation commonly follows minor trauma, predominantly to the foot and hence is seen more among the barefoot-walking populations, common among adult males aged 20 to 50 years. The hallmark triad of the disease includes tumefaction, fistulization of the abscess, and extrusion of colored grains. The color of these extruded grains in the active phase of the disease offers a clue to diagnosis. Radiology, ultrasonology, cytology, histology, immunodiagnosis, and culture are tools used in diagnosis. Recently, DNA sequencing has also been used successfully. Though both infections manifest with similar clinical findings, Actinomycetoma has a rapid course and can lead to amputation or death secondary to systemic spread. However, actinomycetomas are more responsive to antibiotics, whereas eumycetomas require surgical excision in addition to antifungals. Complications include secondary bacterial infections that can progress to full-blown bacteremia or septicemia, resulting in death. With extremely disfiguring sequelae, following the breakdown of the nodules and formation of discharging sinuses, it poses a therapeutic challenge.

MRI findings in cranial eumycetoma

Cranial eumycetoma (CE) due to direct inoculation of Madurella grisea into the scalp is extremely rare. We describe a case of CE caused by direct inoculation of M. grisea with the characteristic MRI findings of the "dot-in-circle" sign and a conglomeration of multiple, extremely hypointense "dots."

Radiologic characteristics of sinonasal fungus ball: an analysis of 119 cases

BACKGROUND

It is important to differentiate sinonasal fungus ball from non-fungal sinusitis and other forms of fungal sinusitis in order to determine the optimal treatment. In particular, a sinonasal fungus ball, a non-invasive fungal sinusitis, can be characterized by radiologic findings before surgery.

PURPOSE

To differentiate a sinonasal fungus ball from other types of sinusitis and determine optimal treatment on the basis of radiologic findings before surgery.

MATERIAL AND METHODS

We studied 119 patients with clinically and pathologically proven sinonasal fungus balls. Their condition was evaluated radiologically with contrast-enhanced CT (99 patients), non-contrast CT (18 patients) and/or MRI (17 patients) prior to sinonasal surgery.

RESULTS

Calcifications were found in 78 of 116 (67.2%) patients who underwent CT scans for fungus ball. As opposed to non-contrast CT scans, contrast CT scans revealed hyperattenuating fungal ball in 82.8% and enhanced inflamed mucosa in 65.5% of the patients, respectively. On MRI, most sinonasal fungal balls showed iso- or hypointensity on T1-weighted images and marked hypointensity on T2-weighted images. Inflamed mucosal membranes were noted and appeared as hypointense on T1-weighted images (64.7%) and hyperintense on T2-weighted images (88.2%).

CONCLUSION

When there are no calcifications visible on the CT scan, a hyperattenuating fungal ball located in the central area of the sinus with mucosal thickening on enhanced CT scans is an important feature of a non-invasive sinonasal fungus ball. On MRI, a sinonasal fungus ball has typical features of a marked hypointense fungus ball with a hyperintense mucosal membrane in T2-weighted images. A contrast-enhanced CT scan or MRI provides sufficient information for the preoperative differentiation of a sinonasal fungus ball from other forms of sinusitis.

Madura foot masquerading as a hemangioma

Mycetoma, also known as Madura foot, is a rare soft-tissue granulomatous infection caused by Actinomyces or true fungi. The MRI “dot-in-circle” sign has been described as a characteristic finding of mycetoma. This sign represents spherical T2 bright masses containing central and intervening low-signal-intensity foci. However, other soft-tissue masses can have similar appearances. We present a case of a Madura foot that was erroneously given the imaging diagnosis of soft-tissue hemangioma due to the presence of serpiginous enhancing masses with the “dot-in-circle” sign (believed to be due to phleboliths).

Infections caused by Scedosporium spp

Scedosporium spp. are increasingly recognized as causes of resistant life-threatening infections in immunocompromised patients. Scedosporium spp. also cause a wide spectrum of conditions, including mycetoma, saprobic involvement and colonization of the airways, sinopulmonary infections, extrapulmonary localized infections, and disseminated infections. Invasive scedosporium infections are also associated with central nervous infection following near-drowning accidents. The most common sites of infection are the lungs, sinuses, bones, joints, eyes, and brain. Scedosporium apiospermum and Scedosporium prolificans are the two principal medically important species of this genus. Pseudallescheria boydii, the teleomorph of S. apiospermum, is recognized by the presence of cleistothecia. Recent advances in molecular taxonomy have advanced the understanding of the genus Scedosporium and have demonstrated a wider range of species than heretofore recognized. Studies of the pathogenesis of and immune response to Scedosporium spp. underscore the importance of innate host defenses in protection against these organisms. Microbiological diagnosis of Scedosporium spp. currently depends upon culture and morphological characterization. Molecular tools for clinical microbiological detection of Scedosporium spp. are currently investigational. Infections caused by S. apiospermum and P. boydii in patients and animals may respond to antifungal triazoles. By comparison, infections caused by S. prolificans seldom respond to medical therapy alone. Surgery and reversal of immunosuppression may be the only effective therapeutic options for infections caused by S. prolificans.

A painful thorn in the foot: a case of eumycetoma

Madura foot or mycetoma is endemic in many developing countries. It is occasionally seen within the United States due to increasing international travel but it may sometimes be acquired within US soil. Herein, we present a case of a patient with a diagnosis of mycetoma acquired through trauma to the foot. In addition, we discuss the epidemiology, etiological agents, clinical presentation, diagnosis, and treatment of mycetomas. Clinicians need to recognize mycetoma early and institute treatment promptly to reduce the substantial morbidity associated with this devastating infection.

Pathological fractures in mycetoma

Pathological fractures in mycetoma are a rarity and only 1 patient was reported in the literature. We report an unexpectedly high incidence of pathological fractures in mycetoma seen at the Mycetoma Research Centre, Khartoum, Sudan over a 10-year period. Plain radiographs of 517 patients with confirmed mycetoma in various body sites were reviewed and correlated with the clinical presentation of the patients. Pathological fractures were detected in 12 patients (2.3%). The explanation of this high incidence is unclear. Pain-reducing agents produced by mycetoma may be the reason that these fractures were overlooked clinically.

Mycetoma caused by Madurella mycetomatis: a neglected infectious burden

Tropical eumycetoma is frequently caused by the fungus Madurella mycetomatis. The disease is characterised by extensive subcutaneous masses, usually with sinuses draining pus, blood, and fungal grains. The disease affects individuals of all ages, although disability is most severe in adults who work outdoors. Compared with major diseases such as tuberculosis, malaria, and HIV, disease from M mycetomatis is underestimated but socioeconomically important. Many scientific case reports on mycetoma exist, but fundamental research was lacking until recently. We present a review on developments in the clinical, epidemiological, and diagnostic management of M mycetomatis eumycetoma. We describe newly developed molecular diagnostic and gene typing procedures, and their application for management of patients and environmental research. Fungal susceptibility tests have been developed as well as a mouse model of infection. These advances should greatly further our understanding of the molecular basis of eumycetoma.

Madura foot due to Actinomadura madurae: imaging appearance

We report a rare case of actinomycetoma of the foot (madura foot) due to Actinomadura madurae in a patient living in a Temperate Zone country. Plain radiographs and MRI imaging were useful in establishing the diagnosis.

MRI of mycetoma of the foot: two cases demonstrating the dot-in-circle sign

Radiological and histological findings of two patients with fungal mycetoma of the foot are presented. MRI revealed multiple 2-5 mm lesions of high signal intensity interspersed within a low-intensity matrix. Within many of the lesions a minute low-intensity focus was identified. Ultrasound showed distinct hyperechoic foci within a hypoechoic mass. We speculate that the low-signal matrix represents fibrous tissue, the high-intensity lesions correspond to granulomata and the central low-signal focus to the characteristic organised fungal elements (grains) present in this condition. This "dot-in-circle sign" on MRI reflects the unique pathological features of mycetoma and is likely to be a highly specific sign for this lesion.

New radiographic classification of bone involvement in pedal mycetoma

OBJECTIVE

The purpose of this study was to classify the pattern, extent, and severity of bone involvement in mycetoma of the foot.

CONCLUSION

In this classification, stage 0 indicates the presence of soft-tissue swelling without bone involvement. Stage I refers to the extrinsic pressure effects on the intact bones in the vicinity of an expanding granuloma. Stage II results from irritation of the bone surface without actual intraosseous invasion. Cortical erosion and central cavitation occur in stage III. If the disease spreads longitudinally along a single ray, stage IV is established; horizontal spread along a single row represents stage V. Multidirectional spread due to uncontrolled infection is classified as stage VI.

Pulmonary actinomycosis with thoracic soft tissue mass: a rare onset form

Actinomycosis is unusual, and rare especially when the lung and the thoracic wall are involved. It is more frequent in immunocompromised patient. US, CT, or MRI are imaging methods of diagnosis with high sensibility to recognise the disease and are able to the management. We point out a rare case in a normal teenager with thoracic abscess.

Imaging of spinal infection

MR imaging is the modality of choice for the detection, staging, and differential diagnosis of inflammatory disorders of the spine. Infectious spondylitis is characterized by the involvement of two adjacent vertebrae and the intervening disk with severe BME and early destruction of the end plates. The disk space is narrowed and typically exhibits water-equivalent signal intensity on T2-weighted or STIR images. Prevertebral and epidural extensions, abscess formation, enhancement of the BME, the disk space, and the surrounding granulation tissue are well demonstrated by gadolinium-enhanced images. Cervical spondylitis frequently involves more than one level. Bone marrow abnormalities may be subtle at this level and increased signal intensity of the disk space on T2-weighted or STIR images is an important finding. The risk for neurologic complications is increased. Granulomatous infections caused by tuberculosis, brucellosis, fungi, and parasites, including hydatid disease (Echinococcus), are frequently associated with imaging findings different from those seen with nonspecific bacterial infection. In patients with chronic infectious spondylitis, diffuse reactive bone marrow changes with decreased signal intensity on T1-weighted images, increased signal intensity on T2-weighted and STIR images, and increased uptake after gadolinium administration may occur. This phenomenon is probably caused by reactive bone marrow stimulation, simulating diffuse hematologic neoplastic disease. Erosive intervertebral osteochondrosis with bandlike disk gadolinium enhancement and BME, which is commonly associated with local pain, is the most important differential diagnosis of bacterial spondylitis.

Recurrent mycetoma of the foot

Mycetoma, also known as madura foot, is a local, chronic, slowly progressive disease with the classic presentation involving tumefaction, multiple draining sinuses, and grain-filled pus. It is primarily produced by either a bacteria (actinomycetoma) or a fungal (eumycetoma) organism. Determining the causative organism is fundamental to the treatment process. All types of mycetoma infections should be treated with early surgical debridement and tissue culture. Tissue should be sent for gross, microscopic, and histopathologic evaluation. In addition to surgical management, these patients should be managed adjunctively with a prolonged course of chemotherapy. Patients with actinomycetoma are treated with an antibiotic and can expect to have a clinical cure with little chance for recurrence, whereas, patients with eumycetoma are treated with an antifungal agent and usually do poorly with a high rate of recurrence. The case presented involved an infection due to Actinomadura madurae (Nocardiaform madurae) and demonstrates successful treatment with surgical resection and prolonged doxycycline chemotherapy.

Radiological manifestations of madura foot in the Eastern Province of Saudi Arabia

A total of 29 patients with mycologically and histopathologically proven mycetomas were examined for radiological manifestations from April 1984 to March 1996. Twenty cases were actinomycotic mycetomas, while nine were maduromycotic mycetomas. Plain x-rays of the regions of interest were taken in all the cases and CT scan was performed on five selected cases to compare the findings. Soft tissue changes were observed in all the examined cases, while bony changes were observed in 16 (55.7%). CT scan is useful for showing soft tissue changes, erosion and destruction of bone in cases with an early infection only, which cannot be demonstrated in plain radiographs.

Aspergillus flavus mycetoma and epidural abscess successfully treated with itraconazole

Aspergillus spp. rarely cause mycetomata. We report a patient with diabetes and nephrotic syndrome with Aspergillus flavus mycetoma of the back, with the development of an epidural abscess, diskitis and vertebral osteomyelitis. The patient was successfully treated with decompressive laminectomy and a 14-month itraconazole regimen. Serial serum itraconazole levels and quantitative Aspergillus antigen levels were performed. This is the second reported and first extrapedal case of mycetoma caused by A. flavus.

Mycetoma

Mycetoma is a chronic infectious disease, most commonly caused by Madurella mycetomatis, that remains localized, involves cutaneous and subcutaneous tissue, fascia, and bone, and is noncontagious. The disease is characterized by tumefaction, draining sinuses, and the presence of sclerotia. The 31 fungi known to cause mycetoma are associated with soil and woody plants. A chronic, tumor-like deforming disease develops during subsequent years following the introduction of the etiologic agent via localized trauma. Combined surgical and medical management with ketoconazole results in the best outcome.