Unusual Manifestations of Oral Follicular Lymphoid Hyperplasia Mimicking Oral Lichen Planus ^†

Follicular lymphoid hyperplasia (FLH) of the oral cavity is a rare and poorly understood lymphoproliferative disorder which may be confused clinically and histologically with malignant lymphoma. The condition has been described in different districts: notably skin, gastrointestinal tract, lungs, nasopharynx, larynx, and breasts. Rarely, the oral cavity may be involved [1]. The disease occurs in a wide age range, namely 38 to 79 years old patients. FLH is more common in women (ratio 3:1) [2]. Clinically, the manifestation is a firm, painless, nonulcerated, slowly growing mass or swelling on the one side of the palate. Occasionally, the lesions may be multifocal, and the patients may have bilateral involvement. Usually, the lesion is soft and either colored or non-colored [3].

A 45-year-old female non-smoking patient came to our hospital complaining of relapsing-remitting pain on bilateral buccal mucosa.

She was suffering from Hashimoto’s Thyroiditis, but she was not assuming any replacement therapy. She underwent bimaxillary Orthognathic Surgery several years ago.

Clinical examination revealed the presence of bilateral atrophic lesions surrounded by white striae, involving the buccal mucosa (Figure 1). The clinical suspect was of a symptomatic lichen planus. An incisional biopsy of the left buccal mucosa was performed and the pathological assessment showed hyperplastic aspect of the epithelium but otherwise unremarkable. The subepithelial tissue contained a dense follicular lymphoid infiltrate. The interfollicular tissue contained small lymphocytes, occasional large lymphocytes, plasmacells and a few eosinophils (CD20+, CD3+, Regular: Bcl2, Bcl6, CD10, Mib1) (Figure 2). An incisional biopsy was repeated on the right buccal mucosa with the same pathological assessment. The specimens were analysed by a second pathologist, who confirmed the diagnosis.

To complete the diagnostic process, in agreement with the haematologist, blood exam, an ultrasonography of the abdomen, a chest x-ray and a protein electrophoresis were performed. The exams ruled out any systemic involvement. The joint assessment of such results and of the previous investigations allowed the diagnosis of oral lymphoid hyperplasia. The patent has been followed up for 10 months with no sign of worsening of the lesions, which remained light symptomatic.

Oral manifestations of FLH, have been reported in just around 30 cases; they showed the presence of swelling in particular of the hard palate. To the best of our knowledge, this is the first reported case of bilateral buccal mucosa involvement mimicking lichen planus.

FLH is a rare and benign lymphoproliferative disorder, interdisciplinary efforts are mandatory to avoid diagnostic time delay.