Primary giant mucosa-associated lymphoid tissue lymphoma of the lower lip: a case report and literature review

Abstract

Oral lymphomas are rare and difficult to diagnose, with Mucosa-Associated Lymphoid Tissue (MALT) lymphoma most commonly affecting older adults, particularly women. MALT lymphoma of the lip is exceptionally rare, and its cause is poorly understood. We present a case of primary giant MALT lymphoma of the lower lip, explore its clinicopathological features, and review relevant literature. An 83-year-old woman developed a painless, pea-sized swelling on the right lower lip over three years, which gradually increased in size without discomfort. She had no history of chronic infections or autoimmune diseases, and all investigations were unremarkable. Examination revealed a spherical, indurated mass on the left lower lip, measuring 8 cm, with no regional lymphadenopathy. Histology and immunohistochemistry confirmed extranodal marginal zone B-cell lymphoma of MALT. This case underscores the need to consider lymphoma in the differential diagnosis, even without systemic symptoms. Patients with oral MALT lymphoma often achieve complete remission after treatment, but diagnosing it can be challenging, requiring immunohistochemical testing for confirmation.

Keywords: Lip; Lymphoma; Mucosa-associated lymphoid tissue (MALT); Non-Hodgkin lymphoma; Oral mucosa.

Fig. 1

The preoperative extraoral photograph reveals a well-defined, fluctuant mass on the right lip with visible vascular dilation and minimal tenderness

Fig. 2

MRI scan in axial (A), sagittal (B), and coronal views (C) revealing a round to oval well-defined lesion in the right cheek and lower lip measuring 74 mm × 92 mm × 85 mm

Fig. 3

An intraoperative photo shows (A) the mass during primary resection with attempted dissection from the overlying skin, (B) the mass completely removed without adhesion during extended resection, (C) direct closure deemed unfeasible, leading to the design of a local pedicled flap, and (D) reconstruction of the defect with the pedicled flap and surface layer suturing

Fig. 4

The gross surgical specimen of MALT lymphoma from the lower lip

Fig. 5

(A) Frontal view photograph of the patient 7 days postoperatively, (B) Two months after surgery with satisfactory result

Fig. 6

(A, B, C) A hematoxylin and eosin (H&E) stained section shows a diffuse proliferation of small to medium-sized tumor cells with a uniform appearance and no residual salivary gland tissue. (D, E) Immunohistochemical staining demonstrates diffuse and uniform expression of CD20 (D), with membrane positivity, and PAX-5 (E), with nuclear staining in the tumor cells. (F) The tumor cells exhibit strong and diffuse positivity for BCL-2. (G) Markers associated with follicular center B cell differentiation are not expressed in the tumor cells. (H) Scattered T lymphocytes within the tumor population are CD3-positive. (I) The Ki67 proliferation index is low within the tumor cells. (J) EBER (FISH) testing is negative