What causes recurrent abscesses in the thigh and forearm?

Recurrent Abscesses in Thigh and Forearm: Causes and Evaluation

Recurrent abscesses at these sites are most commonly caused by local anatomical factors (pilonidal cyst, hidradenitis suppurativa, foreign material), Staphylococcus aureus colonization (including MRSA), or underlying systemic conditions like diabetes or Crohn's disease, and require systematic evaluation to identify the specific etiology. 1, 2

Primary Causes to Investigate

Local Anatomical Factors

• Search first for structural causes that perpetuate infection: pilonidal cysts, hidradenitis suppurativa, or retained foreign material, as eradication of these can be curative 1, 2
• For thigh abscesses specifically, consider intra-abdominal pathology extending through natural anatomical pathways (psoas muscle, femoral canal, obturator foramen, sacrosciatic notch), particularly if there is history of colorectal surgery, malignancy, or inflammatory bowel disease 3, 4
• Perianal location suggests possible Crohn's disease or anal fistula (associated with one-third of anorectal abscesses) 2

Microbiological Causes

• Staphylococcus aureus colonization (including MRSA) is the leading infectious cause of recurrent skin abscesses in the current era 1, 2
• Obtain cultures from drained abscesses to identify the causative organism and guide antibiotic selection 2, 5

Systemic Conditions

• Check serum glucose and hemoglobin A1c to identify undiagnosed diabetes mellitus, which predisposes to recurrent infections 2
• Consider HIV testing in non-traumatic cases of recurrent abscesses 2
• Neutrophil dysfunction disorders should only be evaluated if recurrent abscesses began in early childhood, not in adult-onset cases 1, 2

Critical Evaluation Steps

History

• Document age of onset (childhood versus adult), pattern and location of recurrences, and symptoms suggesting inflammatory bowel disease 2
• Inquire about previous abdominal surgery, radiotherapy, or malignancy (especially colorectal), as these increase risk of intra-abdominal sources 4
• Deep, vague back or hip pain radiating to buttock and leg may indicate intra-abdominal or retroperitoneal pathology extending to the thigh 4

Physical Examination

• Perform careful perineal inspection and digital rectal examination to identify perianal disease or fistulas 2
• Examine for signs of hidradenitis suppurativa (axillary, inguinal, or perianal involvement with scarring and sinus tracts) 2
• Assess for lymphedema or venous insufficiency, which can predispose to recurrent infections 1

Laboratory and Imaging

• Obtain blood cultures if patient appears systemically ill or bacteremic 2
• Consider abdominal/pelvic imaging (CT) for thigh abscesses to exclude intra-abdominal source, particularly with history of abdominal surgery or malignancy 3, 4

Common Pitfalls to Avoid

• Do not miss local anatomical causes that require definitive surgical correction, not just repeated drainage 2
• Do not assume adult-onset recurrent abscesses indicate immunodeficiency; neutrophil function testing is only indicated for childhood-onset disease 1, 2
• Do not delay drainage while pursuing workup, as antibiotics alone are insufficient without source control 2, 5
• For thigh abscesses with unclear etiology, maintain high suspicion for intra-abdominal pathology, especially in patients with previous colorectal surgery—delayed diagnosis can progress to necrotizing fasciitis with high mortality 4

Management Approach

• Incision and drainage remains the primary treatment for all abscesses, with culture and sensitivity testing of drainage 1, 2, 5
• After acute treatment, consider 5-day decolonization regimen (intranasal mupirocin twice daily plus daily chlorhexidine washes) for S. aureus-related recurrences, though efficacy data in the MRSA era are limited 1, 2, 5
• Treat underlying predisposing conditions: optimize diabetes control, address lymphedema with elevation and compression, treat interdigital tinea pedis 1