CASE REPORT
A 55-year-old Indigenous Australian male living in remote Central
Australia was admitted to Alice Springs Hospital in December 2015 for
pain and swelling at the right calf resulting in a limp. For context,
Central Australia is a rural region of over 1,000,000
km2 comprising approximately 10% of the total
Australian landmass (Figure 1). It is sparsely populated by about 60,000
people.(4) Of these, approximately 40% are Indigenous Australians who
are more likely to suffer from numerous chronic diseases and have poor
health literacy than their non-Indigenous counterparts.(5) Alice Springs
Hospital is the referral facility for this vast remote area.
The patient’s relapsing-remitting symptoms had begun in 2012 following a
fall which, according to him, did not cause traumatic injury or skin
penetration. He was reviewed in the Orthopaedic clinic in 2014 where he
was noted to have an antalgic gait with a range of motion at the right
knee of 90-140° and crepitus on movement, and a palpable medial
gastrocnemius lesion. MRI of the right leg showed heterogeneous
thickening of the medial gastrocnemius/soleus measuring 35×28×147 mm
with unusual tubular extension into the central aspect of the medial
gastrocnemius favouring post-injury haematoma, but raising the
possibility of a neoplastic process (Figure 2). Unfortunately, he was
lost to hospital follow-up until October 2015 when a further Orthopaedic
outpatient review showed no change in the morphology or character of the
lesion and continued observation was recommended.
His past medical history included poorly-controlled type 2 diabetes
mellitus complicated by macroalbuminuria, hypertension, hyperlipidemia,
obesity, complete heart block requiring pacemaker insertion,
osteoarthritis of the right knee and left shoulder, and right leg
varicose veins. His regular medications were aspirin 100 mg daily,
atorvastatin 40 mg daily, gliclazide MR 120 mg daily, metformin XR 2 g
daily, perindopril/indapamide 10/2.5 mg daily, sitagliptin 100 mg daily,
and tadalafil 20 mg as required. On examination at the time of
admission, there were distended superficial veins below the knee, and
marked hard swelling and tenderness of the ankle and right calf to the
level of the popliteal fossa. He was afebrile with a pulse rate of 96,
respiratory rate of 22, blood pressure of 99/90 mmHg, and oxygen
saturation of 97% breathing air on admission. C-reactive protein was
raised at 177 mg/L (normal range 0-5), as he had a neutrophil
leukocytosis with total white cell and neutrophil counts of
16.3×109/L (4-11) and 10.4×109/L
(2.0-7.5), respectively.
A CT scan was performed to characterize the lesion further. This again
showed a cystic morphologically heterogenous structure, but also that it
had increased in size to 38×49×156 mm with a larger solid component,
again raising the possibility of sarcoma (Figure 3). This differential
diagnosis was also supported by the peripherally-enhancing,
multi-loculated nature of the lesion. The patient remained an inpatient
under the General Surgical team for three days, where he received
empirical cefazolin 1 g eight-hourly. Aspiration of the lesion for
histological and microbiological examination was planned, but deferred
by the patient to February 2016 when it was performed under ultrasound
guidance.
The aspirate demonstrated an inflammatory exudate comprising primarily
neutrophils and pigment-laden macrophages compatible with abscess. No
malignant cells were seen, but culture yielded pure growth ofPantoea spp. susceptible to amoxicillin/clavulanate, cefazolin,
ciprofloxacin, gentamicin, and trimethoprim/sulfamethoxazole but
resistant to ampicillin. Identification to species level was precluded
by laboratory technological limitations but, given the culture result,
the patient was referred to the Infectious Diseases clinic where he was
seen in April 2016. He reported never feeling systemically unwell or
febrile, and that, subsequent to the aspiration, the pain and swelling
had improved to the extent he was able to walk normally. The calf mass
remained palpable and hard to touch (Figure 4), but CRP had decreased to
11 and he no longer had a leukocytosis. Investigations for
immunodeficiency revealed no lymphocyte deficiency and negative serology
for HIV and Strongyloides , but he was infected with HTLV-1, in
keeping with the very high prevalence in Indigenous Central
Australians.(6) A detailed occupational and exposure history was taken,
in which he denied performing agricultural work or gardening in the
course of his work as an Aboriginal Health Worker or recreationally, but
for cultural reasons would go into the desert surrounding his rural
community when required.
To confirm that the lesion was, indeed, an abscess a second aspiration
and tissue core biopsy was performed. Again, no malignant cells were
seen and pure growth of Pantoea spp. was cultured. Insufficient
tissue was obtained to draw a definitive histological conclusion, but
the patient refused a second attempt as well as any surgical
intervention. As such, he was commenced on amoxicillin/clavulanate
875/125 mg in May 2016 for six weeks, ciprofloxacin being
contraindicated because of his history of arrythmia.
Despite successful completion of antibiotic therapy, the lesion was
still obvious at follow-up in October 2016 and the patient reported
similar symptom exacerbations in the preceding months which would
spontaneously resolve. His case was, thus, discussed at a specialist
sarcoma multi-disciplinary meeting where the consensus opinion was that
an abscess, rather than malignancy, was the most likely diagnosis.
Ongoing surveillance with imaging was recommended but the patient was
lost to follow-up until 2020, when an ultrasound scan requested by his
general practitioner showed persistence of the mass which had organized
into three separate collections measuring 150×25mm, 27×10 mm, and 31×28
mm. The patient declined further intervention for this problem and, at
the time this report was written in 2022, remained systemically well.
Apart from the six weeks of amoxicillin/clavulanate commenced in 2016,
he had not had any extended antibiotic courses for the abscess.