A rare case of upper lip schwannoma: A case report with analysis of the histological, immunohistochemical and pathogenesis aspects

Abstract

Introduction and importance: Schwannoma, a benign tumor originating from Schwann cells, is a rare case found intraorally. The tongue, palate and buccal mucosa are the most common sites of intraoral Schwannoma while it is very rarely found on the lips. Previous studies reported only twelve cases of Schwannoma on the upper lip. The etiology of Schwannoma is unknown, but in some literature, Schwannoma occurs due to a defect in the NF2 gene. Management of Schwannoma is excision of the capsule. The prognosis is good, and the recurrency is low. This article reports a rare case of upper lip Schwannoma in adolescent and its management with its histological, immunohistochemical and pathogenesis aspects.

Case presentation: A 16-years old female presented a painless, semi-solid, mobile lump on the upper lip measuring of approximately 1.5 × 3 cm that had similar color with the surrounding tissue. The lump appeared 7 years ago.

Clinical discussion: Excision of the capsule and margins of the tumor. Histopathological examination showed a unique feature of Schwannoma, the Verocay bodies. Subsequent immunohistochemical examination of S100 protein showed a classic type of Schwannoma.

Conclusion: Upper lip schwannoma is a very rare tumor, and this type of tumor cannot be distinguished from other benign soft tissue tumors based on clinical findings. Immunohistochemical results are in accordance with the Histopathological results for the final diagnosis of Schwannoma. Schwannoma can be used as a differential diagnosis in cases of lumps on the lips with sessile, similar color like surrounding tissue, painless, and movable features.

Keywords: Excision; Schwannoma; Tumor; Upper lip.

Fig. 1

(A) Extraoral examination revealed swelling of the upper lip. (B) Upper lip had a sessile lump on the lip 1.5 × 3 cm, soft consistency, similar color with the surrounding tissue, painless, and movable.

Fig. 2

(A) Excision and evacuation of the tumor. (B) Macroscopic appearance of the tumor with the size of 1.5 × 3 cm.

Fig. 3

Histological analysis (A) HPA image at 10× magnification, showing monomorphous tumor cells with spindle and wavy oval nuclei appearance, hypocellular areas indicated (Antoni B pattern) by black arrows, and hypercellular areas (Antoni A patterns) indicated by blue arrows. (B) HPA image at 40× magnification showed the arrangement in a palisading pattern of Verocay bodies (shown by arrows), a characteristic of Schwannoma. (C) Schematic image of palisading pattern in Verocay body.

Fig. 4

Immunohistochemical analysis of the excised tumor (A) Neoplasm cells (nucleus and cytoplasm) stained positively on all tumor cells with moderate to strong intensity (IHC S100, magnification 40×), (B) neoplasm cells in the Antoni A pattern with positive stain are shown by the arrow. The stained cells indicate S100 protein with strong intensity (IHC S100, magnification 100×), (C) higher magnification showing the neoplasm cells in the Antoni A pattern with positive stain are shown by the arrow. The stained cells indicate S100 protein with strong intensity (IHC S100, magnification 400×).

Fig. 5

Clinical photograph during the follow-up period. (A) 7th day postoperative follow-up, no dehiscence of the wound, scar was noticed in the operation area, (B) 1-year postoperative follow-up, the wound was completely closed, there was no sign of recurrence, esthetic healing was achieved.