Gluteal Abscess Seeded By Extension Of Psoas Abscess Via Sciatic Fistulization

History: Patient is a 52 y/o M with PMH of DM2 who presented for hip pain for 2 months, worsening over the past 2 weeks. Patient initially reported that he was at work 2 hours prior when he developed sudden onset, severe, right sided hip pain. Denied trauma or falling. Patient denied fevers, abdominal pain, nausea, vomiting, rectal bleeding, weight loss, night sweats or diarrhea but did endorse non-localized chest pain that was associated with non-exertional shortness of breath. Patient was not having any chest pain at present however. The patient was noted to have a history of poor glycemic control and medication compliance in regards to insulin therapy for DM.

Vital signs:

HR 149, BP 95/59, T 98 F (36.7C), RR 26, SPO2 99% RA.

Physical Exam:

CV/Resp: notable for tachycardia with regular rhythm, mildly tachypneic with not increased WOB

Abdomen: soft, nondistended, non-tender, no rebound or guarding

Extremities: large, firm mass noted to right gluteal region, no overlying skin changes, no fluctuance, crepitus or surrounding cellulitis, ROM of hip limited due to patient pain

Labs:

CBC: WBC count 18.25, H/H: 10.0/30.8, Plt: 579k, Bands: 7

CMP: Cr 1.0, Glucose: 565, CO2 21, Na 122, AG 12.

Troponin: <0.015

Lactate: 4.0

EKG:

Sinus tachycardia with short PR. Nonspecific T wave changes. Normal intervals

The patient was initiated as a ‘sepsis alert’ and resuscitation measures were initiated with empiric broad spectrum antibiotics and IVF. CT scanning was performed of the chest/abdomen/pelvis as well as blood and urine cultures to evaluate for source of infection.

CT of the abdomen/pelvis

CT of the abdomen/pelvis displayed an extensive complex mixed air and fluid collection of the right hemipelvis and gluteal musculature. Abnormal appearing SI joint which was thought to represent seeding or sequelae of septic emboli. Additional considerations were also for right SI joint septic arthritis with surrounding intramuscular abscess formation and possibly findings could also represent ruptured colonic neoplasm with superimposed infection and abscess formation.

CT Chest

CT of the chest displayed a small cavitary lesion of the left lingula, 2.1×1.7cm

Clinical Course:

The patient was found to have septic shock secondary to MSSA bacteremia with right sided iliopsoas abscess, retroperitoneal abscess, and gluteal abscess extension of the psoas abscess. Initially there was concern for perforated colon causing enterococcal infection causing the abscess extension and exploratory laparotomy was performed. Ex-lap did not show any significant colon pathology or involvement. Due to multiple abscesses, there was concern for septic emboli thus TEE was performed that displayed no vegetative valve disease, or ejection fraction abnormality. The pulmonary cavitary mass was thought secondary to septic emboli and not mycobacterium. The patient was treated in the surgical ICU and underwent further incision and drainage of the gluteal extension component with drainage of retroperitoneal abscess augmented by drains placed by Interventional Radiology. An Abscessogram performed showed a sinus fistula tract to the gluteal musculature via the sciatic notch. Subsequently wound care was augmented with wound vac devices. The patient was also noted to have pyelonephritis likely secondary to uncontrolled DM and bacteremia and remained on strict I&O throughout the hospital course with clinical improvement. The patient’s total hospital stay was 12 days. The patient was discharged on oral antibiotics and outpatient wound care.

The patient returned one month later with back pain and increased drainage from the gluteal wound site. He was found to have osteomyelitis of the L3 vertebrae by aspiration biopsy and required additional incision and drainage of the gluteal wound as well as IV antibiotics for osteomyelitis. Blood cultures again returned with MSSA and the patient was placed on long term IV infusion of nafcillin on discharge. Total admission at that time was 11 days.

The patient returned to the ED 10 days later for right sided shoulder pain and was found to have septic arthritis again colonized by MSSA and bacillus sp. The hip wound vac was found to be malfunctioning and extension from hematogenous spread was thought to cause the septic arthritis. The patient underwent arthrocentesis of the right shoulder joint by orthopedics and revision of the gluteal drains by IR/General surgery. The patient had a PICC line revised and was discharged subsequently on 4 additional weeks of IV nafcillin infusion. The patient underwent gluteal drain removal after 4 weeks and was noted to be improved although was left with chronic hip pain.

Case Discussion:

Psoas Abscesses are rare and were often diagnosed postmortem prior to the advent of the CT. (2) “The psoas muscle arises from the transverse processes and the lateral aspects of the vertebral bodies between the 12^th thoracic and the 5^th lumbar vertebrae. From this origin, it courses downward across the pelvic brim, passes deep to the inguinal ligament and anterior to the hip joint capsule to form a tendon that inserts into the lesser trochanter of the femur. The iliacus muscle joins the psoas to insert via the same tendon. The iliacus and psoas muscles typically function as the main hip flexors.

Psoas Abscesses are described as either primary or secondary.

Primary abscesses are the result of lymphatic seeding or hematogenous spread (2-4). Affected patients are often immunosuppressed (DM, HIV, ESRD, IVDU). Most common in children and young adults (2,3,6). Most commonly due to Staphylococcus Aureus (3,6,12,18,25, 26).

Secondary abscesses are the result of direct spread from adjacent structures (vertebra, hip, GI, GU, Aorta) (1-3, 6, 8-22, 24).More commonly polymicrobial, often enteric organisms. (3,6)

Presentation is often with fever, limping, flank or back pain often with radiation to the hip. (1-3,6, 12,23,41) Labs often show elevated inflammatory markers and leukocytosis. (2,6,12, 28) Treatment includes IV antibiotics and abscess drainage either with IR or open. (1,2,3, 18,41, 54,59) Antibiotics should be based on culture data, however, if empiric antibiotics are started they should cover S. Aureus (including MRSA) and enteric organisms. (41)

Reviewing this case, psoas abscesses unless recognized early can result in significant morbidity and downstream complications.

References

Kathryn Tessitore MD

EM PGY-3, chief resident, wife, dog mom. Enjoys baking, outdoor activities, and home renovation. On a quest to make the world’s best chocolate chip cookie.