3. Discussion
Herein, we reported a case of plexiform schwannoma with an unusual size that developing in an unusual location. Generally, Schwann cell tumors are categorized as neurofibromas, schwannomas, and malignant peripheral nerve sheath tumors (MPNSTs). In addition, these tumors can be considered as a manifestation of genetic diseases, such as Neurofibromatosis type 2 (NF-2), carney complex type 1, and schwannomatosis (5).
Schwannoma is considered a benign peripheral nerve sheath tumor that stems from the slow proliferation of Schwann cells (2). The plexiform schwannomas are benign tumors, which develops in a plexiform pattern; nevertheless, the malignant transformation is rarely reported (5). Clinically, this tumor often develops as a solitary subcutaneous or intradermal nodule and grows in a small size, the greatest diameter of which is mostly lower than 2 cm (6). Imaging particularly MRI can be helpful in diagnosis and localization of the lesion before the treatment; however, the diagnosis cannot be confirmed without histopathological studies (7).
From the histopathological view, various nodules which locate intradermally or subcutaneously consist of cellular Antoni A, in which areas with both nuclear palisading and verocay bodies are detected. In contrast to schwannomas, plexiform schwannomas develop in a plexiform configuration including various interconnecting nodules and fascicles in Antoni A areas (8). Plexiform neurofibroma could be considered as a differential diagnosis of plexiform schwannoma from a histological aspect. However, plexiform schwannomas are made of Schwann cells which can be detected via S100 protein staining (9).