Case presentation
History:
A 5-year-old-boy with eczema and food allergies presented with persistently elevated ESR following several intermittent episodes of atraumatic and non-specific leg pain resulting in limping without any other symptoms. In March 2019, a month prior to the onset of these episodes, he was diagnosed with streptococcal pharyngitis which was adequately treated. His leg pain had resolved by August 2019 but the ESR remained elevated. In November 2019, laboratory studies were remarkable for an elevated ASO titer, leukocytosis and thrombocytosis, and elevated levels of complement and immunoglobulins - suggestive of a chronic inflammatory process. However, ANA, RF, and lyme antibodies were all negative. He was evaluated by Cardiology due to a concern for rheumatic heart disease, but his ECHO and EKG were normal. The patient had recurrence of leg pain in February 2020 and due to concern of underlying arthralgia, he was evaluated by Rheumatology. A hip ultrasound (US) was performed to evaluate for synovitis and demonstrated a trace effusion, suggestive of a reactive process. His hip US finding, combined with persistently elevated ESR, ASO and anti-Dnase B prompted initiation of penicillin prophylaxis for post-strep reactive arthritis. LDH, uric acid, ultrasound of the abdomen and doppler of his lower extremities showed no abnormalities. He underwent a second cardiology evaluation with ECHO and EKG, which were again unremarkable.
Five months later, repeat hip ultrasound confirmed resolution of his effusion and he remained fully asymptomatic. However, his ESR and CRP remained elevated, prompting further evaluation. His ASO and DNase B Ab were down trending, so prophylactic penicillin was stopped and he was referred to Infectious Disease for further evaluation. As part of his infectious disease workup, a chest x-ray was done to evaluate for possible granuloma or mass although the patient did not have respiratory symptoms, followed by a chest CT to confirm findings.
Physical exam:
November 2019: Vitals stable. Heart and lung exam unremarkable. MSK exam unremarkable: no tenderness, erythema, full ROM.
January 2020: Vitals stable. Heart and lung exam unremarkable. Right knee pain with deep flexion, but no warmth or effusion.
February 2020: Vitals stable. Heart and lung exam unremarkable. Normal abduction of his hips but hip internal rotation limited bilaterally with no associated pain. No tenderness to palpation of long bones or knees. No effusions noted on 4 extremities.
July 2020: Vitals stable. Heart and lung exam unremarkable. MSK exam unremarkable.
Laboratory or Diagnostic imaging or Procedures:
Fall 2019: ESR (0-15 normal) 85 --> 53, CRP (0-7 normal) 36, Ig G 2053, Ig M 199, C3/C4 253/52, ASO 1954 --> 883, WBC 14, Plts 466, LDH normal, RF normal, ANA negative, Lyme negative, TSH normal, ECHO and EKG normal
Winter 2020: ESR 82 --> 73, CRP 40, ASO 933 --> 907, DNase B Ab 1450 --> 1800, WBC 14, Plts 500s, UA negative, LDH normal, uric acid normal, ECHO and EKG normal, Abdominal US normal, Doppler of lower extremities normal, Hip US showing mild synovial thickening and minimal fluid in the right hip joint
Summer 2020: ASO 455, DNase B Ab 695, ESR 43, CRP 46, LDH normal, uric acid normal, Hip US normal, Chest XR showing 6 cm right upper lobe mass, Chest CT confirming the mass with peripheral enhancement and minimal internal heterogeneous
July 2020: Patient underwent a right upper thoracoscopic lobectomy with chest tube placement in which the mass was completely removed. The margins were negative and there were no other sites of disease on his work-up. Post-operatively, his ESR and CRP normalized to 2 and <1 respectively.
Final Diagnosis:
Pathology results confirmed the mass was an inflammatory myofibroblastic tumor. The decision was made to monitor for recurrence or metastasis with serial images starting 3 months from resection, and no further systemic medication was administered.
Discussion
It is well known that pediatric pulmonary tumors are rare and that there is often a delay in diagnosis due to their rarity and nonspecific clinical presentation. This includes the inflammatory myofibroblastic tumor which is a slow-growing tumor of unclear etiology with characteristics of both reactive and neoplastic lesions. It consists of fibroblastic and myofibroblastic spindle cell proliferation along with an infiltration of inflammatory cells. Previously it had been called an inflammatory pseudotumor or a plasma cell granuloma. Its original WHO classification in 1994 did not define whether this tumor was neoplastic or simply reactive in nature. In 2006, it was clarified to be an intermediary tumor capable of local recurrence but with a low risk of metastasis. The literature to date reports that the risk of local recurrence is significantly decreased following complete surgical excision.While many inflammatory myofibroblastic tumors are asymptomatic, their location tends to dictate the clinical picture. Existing cases in the literature of this tumor affecting the pulmonary system discuss patients with presenting complaints such as cough, fever, respiratory distress, respiratory infection, or hemoptysis. Our case is unique in that our patient's only significant finding was a persistently elevated ESR.
Conclusion
Pediatric pulmonary tumors are rare, and specifically inflammatory myofibroblastic tumors are often difficult to diagnose due to their variable clinical course. It is imperative to consider this tumor as part of a broad differential diagnosis when assessing patients with a persistently elevated ESR in order to avoid delay in treatment.
