Introduction: Malignant peripheral nerve sheath tumors (MPNST) are rare and aggressive sarcomatous tumors with an overall incidence of 0.001% [1] derived from Schwann cells or pluripotent cells of the neural crest [2-8]. MPNSTs are typically seen in patients aged 20-50 years, and usually in the setting of neurofibromatosis type 1(NF1) and following radiation therapy [8]. The most common sites are the trunk and extremities followed by the head and neck area [7, 8].
Presentation of the Case: This case reports a 50-year-old man with a previous diagnosis five years ago of a Plexiform Neurofibroma (NF) in the posterior distal third of the right leg and ankle. In this case, we review the most important pathological findings and review the literature by reason of the rarity of this lesion. Actually, the patient is currently on regular follow-up and ongoing disease extension study in another hospital for surgical or oncologic treatment decisions.
Discussion: The majority of MPNSTs are derived from neurofibroma or they arise de novo in normal peripheral nerves [9, 2]. It is important to focus on the correct diagnosis and especially in the differential diagnosis with other tumors that can mimic MPNST, which include desmoplastic and metastatic melanomas, as well as synovial sarcoma and fibrosarcomatous dermatofibrosarcoma protuberans [10, 11]. In this article, we discuss a case of a patient with a previous diagnosis of plexiform neurofibroma that some years later presents as an enlarging painful mass that extends to the ankle, a rare location for these tumors as described on the pathological findings and review in the literature.
Conclusion: MPNSTs are very rare sheath tumors that must be suspected in patients with NF1, especially with a previous diagnosis or another benign lesion, because this is a very aggressive and rapidly growing disease.