Glomus Tumor of the Lower Extremity Previously Misdiagnosed as Complex Regional Pain Syndrome in Close Proximity to a Myxofibrosarcoma: A Case Report

Abstract

Complex regional pain syndrome (CRPS) is a potentially devastating condition that can result in severe psychological and social morbidity. It is a diagnosis of exclusion, and other pathologic entities must be ruled out first. Glomus tumors are exquisitely painful benign vascular tumors that are most common in the hand and are rarely found in the lower extremity. Here, we present a case of a patient who developed a focus of severe anterior knee pain and tenderness a few months after a car accident that had been misdiagnosed as CRPS for 15 years. She coincidentally developed a sarcoma of her ipsilateral leg distal to this site. Magnetic resonance imaging of the sarcoma included the area of knee pain where, interestingly, it identified a separate small soft-tissue mass. A glomus tumor was diagnosed histologically in a needle biopsy specimen from this mass, which was resected along with the sarcoma. For the first time in 15 years, despite the additional sarcoma surgery, she reported relief of her pain and complete resolution of her "CRPS."

Figure 1

A, Anterior-posterior and (B) lateral radiographs of the left knee demonstrate no acute fracture or dislocation. No evidence of osteolytic or osteoblastic changes about the knee.

Figure 2

Radiographs showing MRI scans of the knee and proximal leg demonstrating both lesions. A, Sagittal T2 with hyperintensity indicative of the ovoid sarcomatous mass on the proximal anterolateral aspect of the leg. B, Sagittal fat-saturated T1 post-contrast demonstrating both the sarcomatous mass and a more proximal circumscribed hyperintensity about the anterolateral aspect of the patella which corresponded with the glomus tumor. Axial fat-saturated T1 post-contrast images (C) proximally at the level of the glomus tumor and (D) distal to the knee at the level of the soft-tissue sarcoma.

Figure 3

Images demonstrating immunohistochemistry of tumor cells showing focal membranous expression of CD99 (A), focal nuclear/cytoplasmic expression of BCL-2 (B), and focal cytoplasmic/membranous expression of smooth muscle actin (C), with vascular smooth muscle cells serving as an internal positive control (arrow).

Figure 4

A, Image showing a circumscribed glomus tumor with a fibrous capsule, dilated vessels (arrows), hemorrhage, and nests/sheets of tumor cells separated by fibrous bands. B, Image showing uniform small round cells with distinct cell borders, centrally placed round-to-oval nuclei with relatively coarse chromatin, and granular eosinophilic cytoplasm. Hematoxylin and eosin staining.

Figure 5

Images demonstrating immunohistochemistry of glomus tumor cells showing strong cytoplasmic expression of smooth muscle actin (A) and calponin (B).

Figure 6

A, Image showing myxofibrosarcoma with dense fibrous bands (asterisk) and a heterogenous appearance, including myxoid (top left) and solid (bottom left) areas. B, Image showing the myxoid area of the tumor with epithelioid tumor cells. Hematoxylin and eosin staining.

Figure 7

A, Image showing epithelioid tumor cells in a myxoid background. B, Image showing medium-to-large tumor cells with epithelioid features, marked nuclear pleomorphism, mitoses (inside box), and multinucleation (arrows). Hematoxylin and eosin staining.