Low-grade fibromyxoid sarcoma arising within the median nerve

Low-Grade Fibromyxoid Sarcoma of the Distal Upper Extremity: A Systematic Review

BACKGROUND

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft-tissue tumor that usually occurs in the proximal extremities and trunk. The purpose of this systematic review was to assess patient demographics, treatment approach, and outcomes for patients with LGFMS of the distal upper extremity.

METHODS

We performed a literature review of case reports and patient reports of LGFMS using Medical Literature Analysis and Retrieval System Online (MEDLINE) and PubMed. Inclusion criteria included case reports and case series of patients with LGFMS of the distal upper extremity. Animal studies, comments, and non-English publications were excluded. Data on available patient demographics, treatment regimen, recurrence, and metastasis were collected.

RESULTS

A total of 365 publications were reviewed. After applying the inclusion and exclusion criteria, 19 articles were included. There were 24 unique patients with LGFMS of the distal upper extremity. The median age was 32 years, and most patients were treated with a surgical excision. Of the 15 reported outcomes, 4 patients had local recurrences, and no patient had metastases or died due to the tumor.

CONCLUSIONS

Although LGFMS of the distal upper extremity is less common, it is critical for surgeons to consider it as a differential. The current approach is a wide excision with negative margins, and chemotherapy or radiotherapy may not be necessary. We found decreased proportions of local recurrence and metastases in the distal upper extremity compared with other anatomical regions. We recommend that surgeons follow up with their patients indefinitely given the slow mitotic rate of LGFMS.

Imaging of non-neurogenic peripheral nerve malignancy-a case series and systematic review

OBJECTIVE

To evaluate the frequency, clinico-pathologic and imaging features of malignant tumors in peripheral nerves which are of non-neurogenic origin (non-neurogenic peripheral nerve malignancy-PNM).

MATERIALS AND METHODS

We retrospectively reviewed our pathology database for malignant peripheral nerve tumors from 07/2014-07/2019 and performed a systematic review. Exclusion criteria were malignant peripheral nerve sheath tumor (MPNST). Clinico-pathologic and imaging features, apparent diffusion coefficient (ADC_min), and standard uptake values (SUV_max) are reported.

RESULTS

After exclusion of all neurogenic tumors (benign = 196, MPNST = 57), our search yielded 19 non-neurogenic PNMs (7%, n = 19/272), due to primary intraneural malignancy (16%, n = 3/19) and secondary perineural invasion from an adjacent malignancy (16%, n = 3/19) or metastatic disease (63%, n = 12/19). Non-neurogenic PNMs were located in the lumbosacral plexus/sciatic nerves (47%, n = 9/19), brachial plexus (32%, n = 6/19), femoral nerve (5%, n = 1/19), tibial nerve (5%, n = 1/19), ulnar nerve (5%, n = 1/19), and radial nerve (5%, n = 1/19). On MRI (n = 14/19), non-neurogenic PNM tended to be small (< 5 cm, n = 10/14), isointense to muscle on T1-W (n = 14/14), hyperintense on T2-WI (n = 12/14), with enhancement (n = 12/12), low ADC_min (0.5-0.7 × 10-3 mm²/s), and variable metabolic activity (SUV_max range 2.1-13.1). A target sign was absent (n = 14/14) and fascicular sign was rarely present (n = 3/14). Systematic review revealed 89 cases of non-neurogenic PNM.

CONCLUSION

Non-neurogenic PNMs account for 7% of PNT in our series and occur due to metastases and primary intraneural malignancy. Although non-neurogenic PNMs exhibit a non-specific MRI appearance, they lack typical signs of neurogenic tumors such as the target sign. Quantitative imaging features identified by DWI (low ADC) and F¹⁸-FDG PET/CT (high SUV) may be helpful clues to the diagnosis.