Type I neurofibromatosis, also referred to as von Recklinghausen’s disease, is an autosomal dominant disease characterized by neurofibromas and abnormal cutaneous pigmentation (cafe-au-lait spot). Its malignant transformation, that is malignant peripheral nerve sheath tumor (MPNST), accounts for about 5–10 percent of all soft tissue tumors^{1, 2)}. Common site of the origin for MPNST is the lower and upper extremities, trunk, head and neck. Its intrathoracic manifestations are very rare.

We have recently experienced a case of intrathoracic MPNST in a patient with von Recklinghausen’s disease.

A 40-year-old man presented to Chonbuk National University Hospital, Chonju, Korea, due to one rapidly enlarging palpable mass in the right neck which was extended to the supraclavicular fossa. He complained of right side posterior neck pain and radiating pain with mild numbness. The motor weakness of his right upper extremity began 4 months ago. Physical examination showed a firm, non-tender and fixed mass associated with ptosis of right eyelid, engorgement of right neck vein, facial swelling and multiple cafe-au-lait spots and pigmented nodular skin lesions on the chest wall and both arms (Figure 1. (A)).

Chest radiography showed an increased homogeneous mass density at right upper lung field with well-demarcated margin and elevation of right side diaphragm (Figure 1. (B)). Magnetic resonance imaging (MRI) scan of the thorax revealed a homogeneous, well-enhanced and well-circumscribed mass measuring 12×10×8 cm. The central portion of the huge mass showed necrotic tissue which was high signal intensity in T-2 weighted image and low signal intensity in T-1 weighted image. The main mass was located in right upper hemithorax and was associated with multiple adjacent lymphadenopathy. The lesion compressed the trachea, esophagus, right carotid and subclavian artery, and encased the brachial plexus (Figure 1. (C)).

Transthoracic needle biopsy was done. In lower power view, it showed nodular growth pattern and conspicious necrosis in the tumor. Densely cellular fascicles alternated with hypocellular zones where the parallel orientation of the cell was lacking (Figure 1. (D)). In the high power view, the tumor cells had markedly irregular contours and high mitotic activity. The nuclei were wavy, buckled, irregular-shaped or occasionally comma-shaped, and the cytoplasm was lightly stained and usually indistinct (Figure 1. (E)). Immunohistochemical stain for s-100 protein showed positive reaction on the cytoplasm of tumor cells (Figure 1.(F)). But, actin and p53 stain were negative.

Von Recklinghausen’s disease (neurofibromatosis type I) is an autosomal dominant disease with an incidence of about 1 in 3,000 live births. Both sexes and all races appear to be affected equally¹⁾. The clinical features of this disorder invariably include cafe-au-lait spots, multiple neurofibromas, lisch nodules or pigmented iris hamartomas^{1, 3, 4)}. The Schwann cell most likely is the cell of origin, but some may originate from perineurium or endoneurium⁵⁾. In our case, the patient showed multiple cafe-au-lait spots and pigmented nodular skin lesions over the chest wall and both arms.

MPNST is a kind of malignant tranformation of type I neurofibromatosis, with an incidence recently reported at about 5–10%⁶⁾. Malignant transformation usually occurs in a neurofibroma, which has been present for an extended period of time. It is heralded by rapid growth of the tumor. The most common anatomic location for malignant schwanomas is the lower and upper extremities, trunk, head and neck, and miscellaneous sites in descending order⁷⁾. But intrathoracic manifestations of MPNST in patients with neurofibromatosis are very rare ^{8, 9)}.

This presented case showed an increased homogeneous mass density at the right upper lung field, with well-demarcated margin and elevation of right hemidiaphragm on chest radiographies. Radiologic study revealed a homogeneous, well-enhanced and well-circumscribed mass measuring 12×10×8 cm. In our case, the mass was located in the thoracic cavity, extending toward the right supraclavicular fossa and associated with multiple adjacent lymphadenopathy. This lesion compressed the trachea, esophagus, right carotid and subclavian artery, and encased the brachial plexus that caused neurologic manifestation, such as radiating pain with mild numbness, motor weakness of right upper extremity and ptosis. In our case, the histologic examinations of the nodular skin lesion showed expansion of endoneurium by myxoid ground substance, such as neurofibroma. The histologic examinations of intrathoracic mass showed consistent with malignant peripheral nerve sheath tumor which was stained with s-100 protein.

Surgical management of intrathoracic neurogenic tumors, even if clinically benign, is advocated¹⁰⁾. Our case was not accessible to operate due to the extension of the tumor to adjacent mediastinal structure, so we started radiofrequency ablation and doxorubicin-based chemotherapy.

We report a case of intrathoracic MPNST in a 40-year-old man with neurofibromatosis. Review of the literature showed that intrathoracic MPNST is very rare but shows highly aggressive manifestation of malignancy and poor prognosis. So, intrathoracic MPNST should be considered in the differential diagnosis of intrathoracic mass in young men with von Reckling-hausen’s disease.