1.
Department of Orthopaedic & Musculoskeletal Trauma
2. Golden Jubilee
National Hospital, Clydebank, Glasgow
Correspondence to:
Mr Kenneth C K Cheng kencheng8@hotmail.com
We report a case
of a 49-year-old man presenting with a history of painful swollen leg, due to a
solitary metastatic deposit in the tibia. After investigation, it was found to
be secondary to infection with Actinomycosis israelii, which is normally a
commensal of the oral and buccal cavity.
Keywords:
Actinomycosis, Actinomycosis
israelii, Tibia
A
49-year-old Caucasian male was initially referred to the on-call physicians,
with a two-week history of increasing right calf pain. The general practitioner
had made a provisional diagnosis of deep vein thrombosis. He also complained of
a productive cough and had noted that, prior to his admission, his weight had
decreased by an undefined amount. He had no dental problems and was
systematically well. He had a past medical history of alcoholism and smoked 50
cigarettes per day.
Routine
investigations revealed no specific abnormality, except for a d-dimer level of
>500 (reference range 0-300 mg/ml). A Doppler ultrasound scan was negative
for deep vein thrombosis. However, a routine chest x-ray revealed an opacity in
his upper left lung. A provisional diagnosis of primary lung carcinoma was made
and investigations were arranged as an outpatient. He subsequently underwent
bronchoscopy and bronchial alveolar lavage. The bronchoscopy revealed no
abnormality. The brushings and aspirate revealed no acid-fast bacilli or
malignant cells. Unfortunately, no specimens were sent for formal culture.
The patient then
underwent a computerised axial tomography guided biopsy of the chest lesion.
This demonstrated fibrous and inflammatory cells with no epithelioid granulomas.
Stains for fungi and acid-fast bacilli were also negative. Once again, there was
no evidence of malignant cells.
However,
throughout this period, the patient continued to complain of increasing right
leg pain. A repeat ultrasound suggested the possibility of an abscess, prompting
referral to the on-call Orthopaedic team.
On
examination, he was found to have a 4 x 6cm swelling over the lateral aspect of
his right proximal fibula. This had been, according to the patient, gradually
increasing in size and tenderness since his initial presentation to the
physicians. Plain radiographs revealed a patchy lucency over the proximal fibula
(see figure 1). Doubt remained about the diagnosis, but no immediate action was
taken, pending the results of the respiratory tests.
Shortly after
this, the patient re-presented complaining of spontaneous discharge from his
right leg. On examination, there was a sero-sanguinous discharge but no frank
pus. Initial cultures revealed no growth. A repeat x-ray revealed further
destruction of the fibula (figure 2). An ultrasound guided biopsy revealed
inflammatory cells but no evidence of malignant cells. A bone scan revealed a
hot spot, not in the fibula as had been anticipated, but in the proximal tibia.
Formal biopsy was undertaken.
The affected skin
edges were excised and the wound explored. Multi-loculated abscesses were
drained and specimens sent for bacteriological and histological assessment.
Histopathology revealed colonies of Actinomycosis israelii.
He
was commenced on intravenous penicillin immediately and during his inpatient
stay his wound improved. He was discharged on oral penicillin. Serial chest
x-rays at the follow-up clinic
showed a gradual reduction in the size of his lung lesion. The patient reported
that his chest symptoms had improved and that he was beginning to put on weight
again.
However, due to
skin necrosis secondary to the multiple abscesses, there was a large cutaneous
defect in his right leg. This was grafted by the plastic surgeons, but the
extensive soft tissue damage provoked an equinus deformity at the ankle and a
fixed flexion contracture at the knee, which is responding to physiotherapy.
Actinomycosis is a
chronic suppurative and Granulomatous infection that produces lesions with
interconnecting sinus tracts that contain granules, composed of microcolonies of
bacteria embedded in tissue elements.1
The first clinical
case of Actinomycosis infection of the soft tissue was described in 1857 by
Lebert, with the characteristic “sulfur granule” initially being described
by Israel in 1878 in human autopsy specimens.2, 3
A similar disease known as “lumpy jaw” had already been found in
cattle in 1826. It is a filamentous bacterium and has been confused in the past
with a fungal disease due to its appearance and the slowly progressive nature of
the lesions, which mimics mycotic illnesses.
In humans, Actinomyces
israelii is a normal commensal of the oral and buccal cavity. The incidence of
infection generally is on the decline, although it still remains a problem in
developing countries.
Infection is more
common in those aged between 30 and 60 years and the male to female ratio is
3:1. It is rare in children.
The most common
presentation of Actinomycosis is cervicofacial infection, however ingestion of
the organism may lead to abdomino-peritonal infection, and tracheo-bronchial
aspiration from the mouth may lead to pulmonary infection.
Currently, there
are 4 species recognised. They are A. israelii, A. naeslundii, A. viscosus and
A. odontolyticus. A. israelli is the predominant cause of infectious disease in
humans.4
In its tracheo-bronchial
form, the patient presents with a productive cough, chest pain or signs of
pericarditis. Chest x-ray can stimulate bacterial pneumonia or neoplasm. Spread
elsewhere leads to the development of solitary or multiple abscesses with
progressive induration, fluctuation and central suppuration with a fibrotic
‘wooden’ texture easily mistaken for carcinoma.5
Osseous involvement usually occurs due to contamination from adjacent
infected soft tissue or less frequently from haematogenous spread. It is
characterised by a combination of lysis and sclerosis on x-ray.
Diagnosis is
difficult and positive cultures are very difficult to obtain, with only a 10 to
20% recovery rate.6, 7 This is often due to the fastidious nature of
the organism, lack of proper culture conditions, prior use of antibiotics and
culture overgrowth from other organisms.6, 7
To increase the
probability of a positive culture, certain requirements must be fulfilled. The
organism should be cultured on brain-heart or blood agar in anaerobic conditions
with a 5% CO2 atmosphere for 4 to 6 days.8 Even when these
requirements are strictly followed, culture results are still poor.
As the diagnosis
is difficult to make, surgery is an important tool in both treatment and
diagnosis, although recurrence is high without concurrent antibiotic therapy.
Oral penicillin, for at least 6 months, is the first line of treatment,
with tetracycline as an alternative.
The authors
concede that, although a definitive diagnosis from the chest lesion was not
obtained initially, given the fact that there were serial radiographic
improvements of the chest lesion and the symptoms abated after the commencement
on antibiotics, the primary source was likely to be tracheo-bronchial.
However, a
confirmed diagnosis of Actinomyces israelli affecting the proximal tibia was
made, leading to involvement of the adjacent soft tissue and its subsequent
presentation.
As there was no
history of external trauma to the affected limb it is likely that this
represents haematogenous spread from the probable lung lesion. Osseous infection
is a rare occurrence, even without the primary respiratory involvement, and has
not been documented in the literature.
This case
emphasises the need for vigilance during clinical assessment of unusual
problems, and the need for careful investigation.
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