Hot Seat Response - 12 yo with right calf mass and limp

Hot Seat Response

By Shilpa Patel

We are presented with the case of a 12 year-old female with right calf swelling, limp and palpable mass on exam. The mass is described by ultrasound as a “heterogeneous mass in deep muscle most consistent with clot” and we have unremarkable labs except for elevated inflammatory markers.

Differential:

Vascular: 

DVT – There is no DVT on ultrasound.  Although a lower extremity ultrasound with Doppler flow generally has a decent sensitivity to rule out DVT, calf veins are sometimes difficult to see and clots can be missed.  That being said, from the information we have, we can say that our patient has a low pre-test probability for DVT.  She is 12, has no systemic disease and no family history of clots.  She is not reported as being overweight or sedentary and we do not know of any recent travel or surgery.   Additionally her calf is described as not being warm or erythematous. 

There is no clinical evidence for compartment syndrome with normal pulses and the amount of swelling described.

Infectious: 

In general we would expect an exam with overlying erythema or warmth with a leukocytosis and fever to go along with the elevated inflammatory markers.   With septic joint , I would expect painful ROM, which is not reported.  With osteomyelitis, after two weeks of symptoms I would expect to see bony changes on plain radiographs.  With an abscess I would expect a different description by ultrasound.  Myositis should have an elevated CK. 

Post traumatic:

Deep hematoma – Our patient denies trauma though not sure how reliable that is. She could have had minor trauma and bled into a hemangioma or vascular mass.  Though, I would expect these to improve, especially given no underlying coagulopathy.  Lymphatic obstruction due to a “clot” in the muscle, could explain the swelling.  Myositis Ossificans is another consideration.  It is a benign ossifying lesion in the muscle that occurs after minor trauma.  In it’s early stages, calcifications may not be present and seen on the plain film and ultrasound imaging can be variable.  Additionally, there may be an elevated ESR and it can be associated with extremity swelling.

Malignancy:

Two primary bone tumors in children, are Ewings and osteosarcoma, but are mostly ruled out by a normal radiograph. In terms of a soft tissue tumor, we have rhabdomyosarcoma or other sarcoma.  These are sometimes associated with soft tissue calcifications on plain radiographs, which we don’t have in our patient.   We also don’t have any sign of systemic disease, weight loss, fever, or metastatic disease – respiratory symptoms or bone marrow disease.  It may be helpful to have a size of the mass.  I am not sure if there is any evidence to support this, but would be more concerned with a larger mass. Malignancy is a rare diagnosis, but would be my reason for the MRI and ortho consult who may want to biopsy the mass.  As this is something I would not want to miss.  I am uncertain of the significance of the elevated ESR and CRP as these are nonspecific but they could be elevated in malignancy.

Management:

I would feel comfortable sending this patient home with plan for an outpatient MRI but would start with an orthopedics consult to get their level of concern regarding malignancy as the etiology of the mass.  If their concern was high, I would admit for further imaging.  Additionally, if the parents seemed unreliable or follow-up was a concern, I may opt for admission for MRI.  If not, I would discharge with a plan for outpatient MRI and would emphasis the need to return for fever, increased pain or swelling, weakness, numbness or tingling or shortness of breath.  I would also call the PMD.