P3C401: Right Hip Pain in an Adolescent: An Unusual Presentation of a Common Condition

Introduction: Acute appendicitis is the most common reason for abdominal surgery in children. Perforation is a complication of appendicitis resulting in intra-abdominal and pelvic abscesses. Most complicated cases occur soon after the initial symptoms. Here, we present a case of unusual presentation of right hip pain, found to be due to a complication of undiagnosed appendicitis.

Case Description: A 16-year-old male with 3 weeks of intermittent right hip discomfort exacerbated by walking was referred to physical therapy. He was noted to have tightness and fullness of the right lower quadrant. An initial hip x-ray was normal. An MRI of the right hip and pelvis demonstrated a 6 x 13cm infiltrative lesion extending across the right iliacus and psoas muscle and multiple large external iliac lymph nodes. The pediatric oncologist was concerned about lymphoma and recommended a needle biopsy.

Before the biopsy, his white blood count was mildly elevated to 12.1 k/ul with 79% neutrophils, and 13% lymphocytes. His hemoglobin was 9.3 g/dl, with platelets of 603 k/ul. The C-reactive protein and the erythrocyte sedimentation were elevated to 167 mg/L and 39 mm/hr, respectively. During the IR-guided biopsy, 275 ml of purulent material was evacuated, and a drain was placed for 8 days. MRI of the abdomen post-drain removal showed a marked decrease
in mass size but with residual inflammatory changes close to the cecum, suggesting subacute perforated appendicitis. The appendix was not visualized. Fluid culture grew Peptoniphilus asaccharolyticus and he was started treated with amoxicillin-clavulanate for 3 weeks.
An elective laparoscopic appendectomy was performed 6 weeks later. Surgical pathology revealed a dilated lumen, foamy histiocytes, and serosal adhesions consistent with interval appendicitis. The patient was diagnosed with perforated appendicitis, causing a pelvic abscess formation from Peptoniphilius asaccharolyticus.

Discussion: In this case, we present a rare manifestation of the most common surgical condition in children. Appendicitis and its complications typically present with fever, loss of appetite, and signs of peritonitis or an acute abdomen.
Our patient did not present with these common features and, specifically, no discernible abdominal pain. His main chief complaint was right hip pain. Over weeks, he gradually developed discomfort and fullness in the right hip and lower abdomen from the abscess collection.
Another rare occurrence in this case is that most perforated appendicitis is commonly polymicrobial. Our patient only grew Peptoniphilus asaccharolyticus, which is a gram-positive anaerobe regarded as a normal flora of the upper respiratory tract, pharynx, GI tract, and vagina that can cause local infections.

Conclusion: This case illustrates an atypical presentation of an urgent and sometimes emergent surgical pediatric condition. In an adolescent with right hip pain, a careful physical examination and imaging should be conducted to exclude intra-abdominal pathology such as perforated appendicitis.