|Year : 2015 | Volume
| Issue : 4 | Page : 298-302
Actinomycetoma of temporal bone: A rare case report
Viresh Arora1, Bhanu Handa2
1 Department of ENT, King Hamad University Hospital, Bahrain
2 Department of Gynaecology, King Hamad University Hospital, Bahrain
|Date of Web Publication||16-Oct-2015|
KHUH, Al Sayh
Source of Support: None, Conflict of Interest: None
Mycetoma is a specific chronic granulomatous disease affecting subcutaneous tissues and the dermis. It is caused by either actinomycetes or fungi. It is endemic and distributed worldwide. The clinical presentation is variable and the diagnosis being made on the presence of pustular exudates and the culture. The treatment depends on the cause, antibacterial medication for the actinomycetoma, and antifungal for eumycetoma. The prognosis is grave if neglected, requiring even amputation of the organ. Although mycetoma mainly involves the extremities, its rare involving head and neck. We report an unusual case of actinomycetoma of the temporal bone which hasn't been reported before, who had presented with a short history of discharging ear and was successfully managed.
Keywords: Actinomycetoma, Mycetoma, Temporal bone
|How to cite this article:|
Arora V, Handa B. Actinomycetoma of temporal bone: A rare case report. Indian J Otol 2015;21:298-302
| Introduction|| |
Mycetoma a chronic slowly progressive destructive disease which usually affects the skin and subcutaneous tissues, is caused either by bacteria actinomycetes or fungi. Mycetoma caused by actinomycetes is termed as actinomycetoma, and mycetoma caused by true fungi is called eumycetoma. It is actinomycetoma in 60% cases and eumycetoma in 40% of the cases.
The organism enters through innocuous local trauma, and spreading along the facial planes leads to progressive destruction of soft-tissue and surrounding anatomical structures. The most commonly affected body parts are foot or lower leg, the dorsal aspect of the forefoot being typical followed by the upper extremity. However mycetoma lesions can occur anywhere on the body.
The disease is characterized by a triad of painless brawny swelling of the tissues, multiple draining sinuses, and the presence of colonial grains which is pathognomic. Mycetoma commonly affects young male adults belonging to low socioeconomic strata, usually barefooted workers in the rural areas engaged in farming and rearing sheep. It is endemic in many tropical and subtropical countries like in India, Pakistan, parts of Africa.
Actinomycetoma is caused by actinomycetes which include the agents Nocardia, Actinomyces, and Streptomyces. It is to be differentiated from actinomycosis which has a similar presentation, is an endogenous suppurative infection caused by Actinomyces israelii or other species of Actinomyces or related bacteria.
Since mycetoma has different etiologies, the treatment of these conditions depends on a confirmed histological and microbiological diagnosis. We report an unsuspected case of actinomycetoma of the temporal bone.
| Case Report|| |
A 55-year-old man presented to us with complaints of left ear discharge for 3 months and pain since 1-month. He had been receiving painkillers and ear drops from the estrogen receptor, but failed to benefit from the treatment. There was no previous history of ear discharge, trauma, operations on the ear, or any other ear associated complaints. There were no complaints of headache, dizziness, radiation of pain. He reported no complaints of restricted or painful mouth opening. He was a known diabetic and had been on metformin for the last 5 years. There were no other known medical disorders.
On inspection, there was noticeable temporal and infratemporal bulge on the left side, which he was not aware [Figure 1]. Examination of the left ear pre- and post-auricular was normal. The external auditory canal (EAC) was full of greenish discharge and granulations were observed in the postsuperior quadrant eroding the attic. There was no tenderness over the temporomandibular (TM) joint or over the bulge and mouth opening was unrestricted. Facial nerve was intact and head and neck examination including the other cranial nerves were normal and there was no cervical lymphadenopathy. A high-resolution computed tomography (CT) of the mastoids with contrast was requested and a complete blood investigations complete blood cell, fasting blood sugar, HbA1c, and erythrocyte sedimentation rate was done. A culture swab was taken from the left ear. A provisional diagnosis of malignant otitis external was made in the light of diabetes and a short history of ear discharge.
Pure tone audiometry revealed a conductive hearing loss of 25 dB. The initial C/s report failed to give any conclusive report except for contamination with Candida. CT scan revealed an enhancing mass in the EAC seen abutting the parotid gland extending along the TM joint with erosion of the attic and tegmen tympani extending to the skull base with involvement of meninges and possible intracranial extension suggesting malignancy of the ear [Figure 2]. An magnetic resonance imaging (MRI) was further advised in light of the findings to rule out malignancy, which revealed enhancing mass in left infratemporal region with enhancement of the meninges and involvement of the cortex of the middle cranial fossa and infiltration the parotid gland, suggesting possible malignancy [Figure 3] and [Figure 4].
|Figure 2: Coronal high-resolution computed tomography of temporal bone in the bone window setting shows bony erosions in left petrous temporal|
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|Figure 3: Axial T1-weighted image show intense enhancement of the soft-tissues in the left infratemporal region and across the deep spaces of neck suggestive of extensive inflammation|
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|Figure 4: Coronal T1-weighted image show intense enhancement of the soft-tissues in the left infratemporal region and across the deep spaces of neck|
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A biopsy was taken from the granulations dense acute on chronic inflammatory tissue reaction with osteoinvasion and Histopathologically suppurative granulomas, were evident, neutrophils surrounding the grains surrounded by lymphohistiocytes, and mixed inflammatory cells like plasma cells exhibiting Splendore-Hoeppli phenomenon was seen [Figure 5]. Microbiology testing revealed pus cells and Nocardia asteroides Bacillus, highly suggestive of actinomycetoma [Figure 6].
Therefore, a diagnosis of actinomycetoma of the temporal bone was made and the patient was started on combination of intravenous gentamicin 1.5 mg/kg twice daily and tablet cotrimoxazole 320 trimethoprim/1600 sulfamethoxazole (DS) mg twice daily orally for 5 weeks in the initial intensive phase. Patient's renal function tests were done before starting gentamicin and were found within the range, and tests were repeated again at 4 weeks. Patient responded well to treatment and showed signs of improvement by the end of 1st week and ear discharge and pain reduced in severity by the 2nd week. The patient was then put on the maintenance phase of tablet cotrimoxazole DS once daily and tablet rifampicin 600 mg once daily for 2 months.
Patient was followed till the biopsy remained negative, and CT scan showed no evidence of the disease.
| Discussion|| |
Mycetoma is also known as Madura foot since it was first seen in Madurai in South-India, but now it is also known to be endemic in other tropical countries. In 70% of cases, foot is involved explaining the synonym Madura foot. The next most common site is hand followed by the scalp. It can be classified as eumycetoma or actinomycetoma caused by fungus or bacteria, respectively. It usually affects poor workers and farmers living in hot dusty climate. Repeated local minor trauma or an unforgotten penetrating injury provides a portal of entry for the organism. The infection by a fungus or a bacterium generally remains localized to the site for few weeks leading to, swelling and nodule formation, which after few months results in discharging sinuses. Histopathologically, an initial neutrophilic response occurs in response to bacterial invasion, later which results in the formation of a granuloma. Clinically, patients experienced painless indurated swelling which develops purulent discharge and progression over the time leads to discharging sinuses with eventual destruction of soft tissue and bone. The infection usually remains contained without involving the regional lymph nodes and the viscera are rarely involved. The main differential diagnoses include more frequently occurring chronic conditions such as osteomyelitis, tuberculosis, and deeper fungal infections like blastomycosis or coccidioidomycosis.
The draining tracts with the presence of grains along with bacteria or fungi are characteristic findings. Mycetoma is characterized by the presence of grains with clumped causative organisms discharging through the sinuses to the skin.
More than 30 species have been reported as etiological agents of mycetoma worldwide. Actinomycetoma is caused by actinomycetes which include Nocardia, Actinomyces, and Streptomyces. The members of the genus Nocardia are Gram-positive filamentous bacteria that are found as saprophytes in the soil. Nocardia brasiliensis is the primary pathogenic organism responsible for cutaneous infection which has a propensity to involve the underlying bone followed by N. Asteroides, which usually causes life-threatening systemic infection., Eumycetoma on other hand is caused by Pseudallescheria boydii or Madurella mycetomatis.
Early diagnosis remains critical for treatment, reducing the associated morbidity with this condition, since the initial presentation can be variable delaying the institution of proper therapy. The characteristic sulfur granules also known as grains containing the organisms vary in size and color helps in making a provisional diagnosis, and can be confusing with the grains of cervicofacial actinomycosis. Actinomycetoma grains are whitish yellow in color not visible to unaided eye, whereas eumycetomas grains are larger and black or white-colored, usually seen with the naked eye. On hematoxylin and eosin (H and E) staining, the grains of actinomycetoma appear homogenous eosinophilic, while these appear blue in the core, surrounded by pink filaments on May-Grünwald-Giemsa staining.
Demonstration of the organisms by Gram-stain staining help in species identification. The organisms found in actinomycetoma are 1 micron thin, branching filaments are Gram-positive and acid-fast, whereas the granules of eumycetoma are Gram-negative, septate hyphae, 4–5 microns thick., The actinomycetoma filaments and hyphae can be stained in biopsy specimen with Gram-stain whereas eumycetoma are Gram-negative. Stains like H and E and May-Grünwald-Giemsa stains show the characteristic grains of the actinomycetoma, while Gomori Methenamine silver or periodic acid-Schiff stains help in delineating the grains of eumycetoma. The staining of crushed discharged granules with special stains like lacto-phenol blue aids in differentiating between the filaments of actinomycetoma and eumycetoma. Morphological differentiation of mycetoma can also be accurately done by fine needle aspiration when deeper tissues are affected.
Histologically, the organisms of actinomycetoma display Splendore-Hoeppli reaction which is a central matted appearance surrounded by a peripheral deposition of eosinophilic infiltrate., Grains of many species have overlapping morphological features a culture is therefore required for correct identification of the causal agent. The grains obtained from the deeper tissue are cultured on Löwenstein-Jensen media for actinomycetoma, and blood agar is used for eumycetoma.
Radiological investigations like CT, MRI not only differentiates from other clinical conditions but also helps in assessment of the extent of soft tissue and bony involvement, thus dictating aggression of treatment required. In T2-weighted images, a characteristic finding a dot in circle sign is seen which shows hyperintense granuloma with central hypointense dots indicating the presence of grains.
Treatment of these two groups requires different regimens hence it is absolutely essential to differentiate between them. In general, actinomycetoma is amenable to medical treatment with antibiotics, sulfonamides being been the mainstay of treatment for nocardial actinomycetoma for many years with reported cure rates up to 90% with a mean duration of therapy >1-year.
Welsh proposed a two-step schedule in the treatment of actinomycotic mycetomas which consists of four injections of penicillin and two of gentamicin daily, in the initial intensive phase of 5–7 weeks. Maintenance phase with amoxicillin/doxycycline and cotrimoxazole till 2–5 months after complete healing. A recent study suggested a modified two-step treatment for actinomycetoma which consists of an intensive phase in which a combined treatment of intravenous gentamicin with oral cotrimoxazole twice daily is given for a period of 4 weeks. In the maintenance phase, cotrimoxazole and doxycycline is given twice daily for 5–6 months.
We preferred to follow the same intensive phase by giving gentamycin and cotrimoxazole, but preferred to add Rifampin in the maintenance phase. It has been reported that the development of resistance to antibiotic occurs on prolonged treatment. Therefore, frequent change in antibiotics is advisable and the inclusion of Rifampin to the regimen helps in prolonged remissions without recurrence.
Eumycetomas on other hand are partial responders to antifungal therapy with azoles like ketoconazole itraconazole, therefore, also require wide surgical debridement.
In our case, the patient was a diabetic with 3 months short history of ear discharge with infratemporal bulge on the same side prompted us to make a clinical diagnosis of malignant otitis externa and was treated on the lines of malignant otitis externa. He was not suspected of having an actinomycetoma since it is neither been reported nor the patient had discharging sinuses and MRI with extensive involvement and erosion of the skull base made us suspicious of the malignant pathology. A Gram-stain failed to reveal the organisms on an earlier occasion and biopsy reported it to be suggestive of actinomycetoma, which was confirmed later with the culture report.
Actinomycetoma of temporal bone has never been reported earlier and we never came across a report in the literature although an isolated case of scalp mycetoma by N. Asteroides without any deeper involvement has been reported. Mycetoma usually affects the extremities which tends to be a slow developing process over the months with a protracted course but such an aggressive involvement within a short duration is not known.
| Conclusion|| |
Actinomycetoma of the temporal bone is a rarity and hasn't before reported before, and thus definite diagnosis after histopathological and microbiological examination is mandatory prompting proper therapy.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]