Neurofibromatosis (NF) is a genetic disease consisting of seven types, of which types 1 to 4 are caused by a dominant autosomal gene mutation; such disease sometimes arises in patients with NF type 1. However, it remains unclear whether the origin of neurofibrosarcoma is directly linked to the incidence of NF type 1, as no reports have been published on this issue. Here, we report a case of NF1-positive multiple neurofibromas with malignant fibrosarcomatous transformation in the pleural cavity.

A 51-year-old male was admitted to our hospital due to fever accompanied by coughing, chest tightness and asthma for more than one month. The preliminary diagnosis was NF type 1, which was pathologically confirmed by a subsequent thoracoabdominal subcutaneous biopsy. The definitive diagnosis was neurofibrosarcoma with a pathogenic NF1 gene. The patient refused surgery and chemoradiotherapy, and died two months later. NF is a genetic disease consisting of seven types, of which types 1 to 4 are caused by a dominant autosomal gene mutation. The case reported belongs to the class of NF1-positive dominant inheritance. Neurofibrosarcoma is a malignant tumor derived from cells surrounding the peripheral nerves. However, due to the lack of previous reports, it remains unclear whether the origin of neurofibrosarcoma is directly linked to the incidence of NF type 1.

We report the first case of NF1-positive multiple neurofibromas with malignant fibrosarcomatous transformation in the pleural cavity.

Neurofibromatosis (NF) is a genetic disease consisting of seven types, of which types 1 to 4 are caused by a dominant autosomal gene mutation[1,2]. Neurofibrosarcoma is a malignant tumor derived from cells surrounding the peripheral nerves and usually occurs in the limbs. Neurofibrosarcoma seldom metastasizes to other parts of the body, although it may reach the lungs by extensive spread along nerve tissues[3]. This disease predominantly affects young and middle-age adults, and sometimes arises in patients with NF type 1. However, it remains unclear whether the origin of neurofibrosarcoma is directly linked to the incidence of NF type 1, as no reports have been published on this issue. Here, we report a case of NF1-positive multiple neurofibromas with malignant fibrosarcomatous transformation in the pleural cavity.

The final diagnosis in this patient was NF1-positive multiple neurofibromas with malignant fibrosarcomatous transformation in the pleural cavity.

The patient refused surgery and chemo-radiotherapy.

The patient died two months later.

This patient was classified as a case of NF1-positive dominant inheritance. NF type 1 rarely involves internal organs, although histological evidence of disease in this case was found in the mediastinum. The majority of neurofibromas in the mediastinum originate from the spinal or intercostal nerves and are located in the posterior mediastinum[4], while the tumor in this case was in the middle mediastinum. This may be associated with the anatomical position of the vagus nerve. Moreover, although NF tends to be benign, in this case, a malignant sarcomatoid tumor was accompanied by ipsilateral pleural effusion, which is rarely encountered. Based on our initial examinations, we made a diagnosis of chylothorax caused by lymphangiomatosis. Lymphangioma is a rare tumor that originates in the lymphatic system, and may develop in any region of the body through which lymphatic vessels pass[5]. On CT imaging, a cystic mass in the mediastinum often appears as a homogeneous low-density area[6,7], although other forms of the disease may be present if the tissue composition of the mass varies[8,9]. In the case described here, preliminary examinations showed that the patient’s pleural fluid was turbid, bloody and chylomicron-positive, which, in combination with the large mass in the pleural cavity, suggested chylothorax. However, further examinations led to the diagnosis of pseudochylothorax. Pseudochylothorax is a type of pleural effusion that is less common than chylothorax, and is predominantly caused by cholesterol accumulation[10,11]. In the case of pseudochylothorax, the proportion of cholesterol-to-triglyceride in the fluid always exceeds 1, with cholesterol > 200 mg/dL and triglyceride < 110 mg/dL.

We report the first case of NF1-positive multiple neurofibromas with malignant fibrosarcomatous transformation in the pleural cavity.