[Carcinoma cuniculatum: An unusual oral tumor].

We report on a case of carcinoma cuniculatum (CC) of the maxillary gingival mucosa. A 60-year-old woman presented with an exophytic gingivo-palatal mass with slow growth and osteolytic evolution. A first performed biopsy was negative for malignancy. The diagnosis of CC was established on the surgical representative biopsy. CC is a rare low-grade variant of squamous cell carcinoma that is usually found in the foot or in oral cavity. The pathognomonic microscopic feature of CC is an endo- and/or exophytic lesion composed by a well differentiated squamous epithelium infiltrating into underlying stroma forming a complex pattern of keratin cores and keratin filled "rabbit warren" crypts. CC is a locally evolutive carcinoma with a usually good prognosis usually without lymph node or distant metastatic evolution.