EXPERIMENTAL AND CLINICAL TRANSPLANTATION

A psoas abscess is a condition with vague symptomatology that is associated with potentially life-threatening suppurative myositis of the iliopsoas muscular compartment. Immunocompromised pa-tients run an increased risk of developing suppurative or chronic abscesses from acute foci. The presence of a solid-organ transplant, and the attendant need for immunosuppressant therapies and impaired renal provide additional factors that could contribute to the comorbidities of this condition.

Here, we present a 61-year-old white man with a functioning renal transplant who developed a chronic psoas abscess associated with an appendicular sinus that required serial computed tomographic-guided drainages during 8 years. We highlight the difficulties and limitations of managing a psoas abscess. We conclude that a conservative approach toward managing a chronic psoas abscess may be associated with good long-term patient and graft functions, with minimal risk to the patient.

Key words : Psoas abscess, Renal transplant, Appendicular sinus, Computed tomography-guided drainage

Psoas abscesses are an uncommon clinical entity that are associated with diagnostic and therapeutic challenges.^1,2 Two types of psoas abscess are recognized. The primary psoas abscess, which generally occurs after haematogenous dissemination of an infectious agent and usually an occult source.^3,4 The secondary abscess, which can be the result of local extension of an infectious process near the psoas muscle.^5,6 Symptoms are often nonspecific. Patients may present with fever, flank pain, abdominal pain, or a limp. The latter occurs as the result of the innervation of the psoas muscle by L2-L4, pain because of its inflammation (sometimes radiating anteriorly to the hip and thigh). Other symptoms include nausea, malaise, and weight loss. Chronic psoas abscesses that are asymptomatic for years are rare, and there is a paucity of literature on this subject. This report describes a case of a chronic psoas abscess, secondary to an undiagnosed appendicular sinus of more than 5 years’ duration in a renal transplant recipient.

A 61-year-old white professional man with a well-functioning renal transplant of 10 years’ duration presented with vague abdominal pain, malaise, and pyrexia. His end-stage renal failure was secondary to adult polycystic kidney disease. He received a deceased-donor renal transplant in his right iliac fossa. He had an uneventful postoperative recovery and was under regular follow-up of the transplant unit.

Two years after his renal transplant, he developed symptoms of severe abdominal pain and sepsis secondary to infected native renal cysts of his polycystic kidneys. He underwent urgent bilateral nephrectomy through a transperitoneal approach. The operative finding of purulent peritonitis with possible ruptured appendix were recorded. The remnant of the appendix was ligated and transfixed, and bilateral nephrectomies were performed.

His postoperative course was complicated by an intra-abdominal collection during the first 2 months. These collections were at the site of right native nephrectomy bed and were drained percuteneously under ultrasound. Microbiology showed Enterococcus and Citrobacter growth. He received a 4-week course of antibiotics. A follow-up computed tomography (CT) scan confirmed no residual abscess after 8 weeks. Initially, there was a good response, but 6 months after his polycystic nephrectomy he again developed symptoms of abdominal pain, fever, and malaise. A CT scan confirmed a psoas abscess that had drained percuteneously under CT guidance. The drain was left in situ for 4 weeks and was then removed after a repeat CT scan showed no residual collection. As a result of his immunocompromised state, he began long-term rotating prophylactic antibiotics (metronidazole 500 mg once daily, ciprofloxacin 250 mg once daily, and amoxicillin 500 mg once daily; 1 month, each, in a rotating cycle) that he took for 1 year and then stopped. He remained completely asymptomatic for about 6 years until he re-presented in the transplant clinic with symptoms of malaise, increasing abdominal pain, and a low-grade fever. He underwent an ultrasound scan that confirmed the recurrence of a psoas abscess. He was restarted on antibiotics, but his symptoms did not improve.

He then had a CT scan followed by CT-guided drainage of his psoas abscess (Figure 1). The culture showed multiresistant Enterococcus Faecalis, alpha-haemolytic streptococci, and Escherichia coli. Because of the persistent drainage, he underwent a sinogram (Figure 2) that showed a possible appendicular or caecal sinus. He had a diagnostic laparoscopy that confirmed an appendicular sinus as the cause of his chronic recurrent psoas abscess. We performed an appendectomy. The patient had uneventful recovery and was dischanged home after 5 days. He remained well for 9 months, during which time had 1 follow-up CT scan that showed minimal resolving collection; however, he then presented again 10 months after his appendectomy with abdominal pain, malaise, and fever.

A repeat CT scan showed recollection of his psoas abscess that had drained under CT guidance. He was placed on intravenous Tazosin for 8 weeks and was observed for symptoms or markers of recurrence of the abscess. Over 1 year later, he remains off antibiotics and has not had a recurrence. His renal allograft functions also have remained stable.

Primary psoas abscesses are more common in developing countries compared with secondary psoas abscesses, which are more prevalent in developed counties.^7,8 The typically described psoas abscess (otherwise known as a Pott abscess) is also known as a tuberculous abscess. The classic triad of symptoms—flank pain, fever, and limitation of hip movements—is not always present.^9,10 In an immunosuppresed patient, many of the symptoms of acute or chronic illnesses may be different or atypical.^11,12 Immunocompromised patients are more at risk of developing chronic abscesses from acute foci, despite being treated vigorously; therefore, follow-up of such lesions (even if asymptomatic) is highly important. Indeed, in renal transplant recipients, renal allograft dysfunction may be the only presentation of an underlying disease that is otherwise asymptomatic.

In the case presented above, the symptoms of psoas abscess were all atypical and there was only mild renal allograft dysfunction. One of the major risk factors for chronicity of his psoas abscess was the need for immunosuppressant therapy. In such cases, the balance between achieving minimum effective immunosuppressant levels to prevent rejection and preserve allograft function versus achieving effective control of infection is difficult. Repeat surgical intervention in this patient presents a challenge because of adhesion formation, with poorly demarcated planes owing to previous surgery. The use of long-term prophylactic antibiotics is not ideal, because of the risk of developing long-term antibiotic resistance. Clinicians are therefore left with the option of monitoring their patients using surrogate markers such as C-reactive protein, and development of symptoms.

There is a paucity of published case reports of psoas abscesses in renal transplant recipients in Europe. All the published case reports of psoas abscess in renal transplant recipients are from developing countries where psoas abscess is otherwise relatively common. To the best of our knowledge, this is the first case report from a developed European country.

In publications by Badurdeen,¹³ Ozgur,¹⁴ and Shohaib,¹⁵ they report successful treatment after surgical intervention, but with a short follow-up. In our case, we have noted that even after presumed initial successful surgical treatment, a psoas abscess may come back or may still be present, but be completely asymptomatic for years. Despite an initial success, the psoas abscess presented itself again after 6 years. We treated the recurrence in our patient with serial radiology-guided drainage after surgical intervention had recurred. He also underwent prolonged broad-spectrum antibiotics. This case highlights the importance of regular long-term follow-up with a high index of suspicion even in the asymptomatic patient where long-term immuno-suppression is necessary in the patient’s long-term care.

Volume: 14 Issue: 4 August 2016

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