Here, we present the case of a 57-year-old male with a history of right posterior thigh melanoma, complicated by recurrence, who presented with a right calf mass. So for his original melanoma and recurrence, excisions were performed. With his new right calf mass, he was evaluated and seen in the outpatient surgical oncology clinic. There was associated warmth and redness at this new mass site, and the patient also had worsening leg swelling. Fine needle aspiration of the mass was performed in a PET scan, demonstrated recurrent melanoma with metastases to the patient's right leg regional lymph nodes. And so you can see in the lower left of the poster an area of increased uptake on the PET scan, which is where the patient's new mass was located. So with this diagnosis, given the findings on PET scan and the biopsy that was performed, the patient was started on Pembrolizumab after being referred to hematology oncology. However, after being started on this regimen, he reported increased pain, pressure, and leg size, with difficulty straightening his leg and impaired mobility. The symptoms were debilitating to the point where he actually required assistance from his wife for ambulation. Due to the development of these symptoms, a DVT ultrasound was ordered and was negative, fortunately, for DVT. However, as there was concern from Hemant that the patient was not responding to his originally prescribed chemo regimen, he was started on a new regimen that included Dibrafinib and Tremetinib. And he was also referred to physical medicine and rehabilitation. So upon initial evaluation in a cancer rehabilitation clinic, because of the patient's pain, he was prescribed Mobic and nightly Tremetol to attempt to provide some pain relief, a compression sleeve for his swelling, and a foot drop orthosis brace for his decreased ankle dorsiflexion. On his chemotherapy regimen, there was significant reduction in metastatic lesion size on repeat imaging, and he also demonstrated improved mobility close to his functional baseline with improvement of his leg pain and pressure. And you'll see the MRI in the top right of the poster. So this was done after he had started his new chemotherapy regimen, and there is improvement at least in the size of the lesion. So the pain was also well controlled with nighttime Tremetol. So the repeat PET CT scans showed near complete resolution of his right leg soft tissue mass and minimal residual FDG uptake. So these findings were thought to be in the setting of compartment syndrome. And so with regards to compartment syndrome, involves classically the pressure of a muscle compartment being abnormally elevated with compromised circulation to the nerve and muscles within that space. Subsequently, the function viability of the structures within that space are threatened. Typically, elevated compartment pressures can occur in the setting of fractures, crush injuries, and other significant trauma. Neoplasia is a pretty rare cause. The pain itself is going to occur with stretching of involved muscles, and there can be associated paresthesias, muscle tightness, and potentially paralysis. So those are the five P's that were taught about, or some of the five P's. Now, meanwhile, melanoma is the third most common cutaneous malignancy, so behind both basal cell and squamous cell carcinoma. The most common sites of metastasis are the skin and subcutaneous tissue, followed by the lungs, liver, bones, and brain. Sun and UV exposure remain the obvious and major risk factors. With enough concern for metastatic melanoma, patients will need chest, abdominal, and pelvic imaging, as well as brain imaging with MRI. So this particular patient displayed findings that were concerning for compartment syndrome in the setting of metastatic melanoma, likely in the setting of tumor expansion in his lower extremity posterior compartment. Fortunately, his symptoms improved with treatment response, and his functional mobility improved considerably as well. So as far as we know, there's only been one other documented case of malignant melanoma causing compartment syndrome. So while certainly a less common cause, it's certainly important to consider neoplasia as a cause of compartment syndrome, particularly in the setting of this patient's known history of malignancy.

melanoma

compartment syndrome

metastatic melanoma

chemotherapy

physical rehabilitation