Peripheral desmoplastic ameloblastoma in adolescent age: clinico-pathological and immunohistochemical analisys of a case

Abstract

The Extraosseous or Peripheral Ameloblastoma (PA) is a rare and benign odontogenic tumour, representing 1% to 5% of all ameloblastomas. It is usually localized in the soft oral tissues, without deep bone involvement. Its biological behaviour is specific, and several authors define PA as a non-infiltrating hamartomatous lesion. Indeed, recurrences rarely occur and progression in malignant tumors appears to be rare. The PA originates from the tooth-forming apparatus and it consists of proliferating odontogenic epithelium, exhibiting the same histological cell types and patterns of the intraosseous counterpart or infiltrating ameloblastoma. The peripheral desmoplastic ameloblastoma (PDA) can be classified as a newly recognized and very rare histological variant. To our knowledge, only a few cases of adult patients affected by PDA have been published. The aim of this paper is to report a case of PDA affecting an adolescent patient. The clinical-pathological and immunohistological features are discussed in order to improve knowledge regarding a correct diagnosis and to differentiate PDA lesions from similar diseases.

Keywords: Immune-histochemistry; peripheral desmoplastic ameloblastoma..

Fig. (1)

Intraoral photograph of soft tissue mass located on the vestibular gingiva in the left maxillary premolars area.

Fig. (2)

TC cross-section scans showing a mild depression in the vestibular plate (cupping) of the left premolar maxillary alveolar process.

Fig. (3)

Intraoral photograph, taken thirty months after surgery: here, the healed vestibular gingiva without any tumor recurrence is shown.

Fig. (4)

Ortopantomograph, thirty months after surgery, showing the intact bone in the left premolar maxillary area.

Fig. (5)

Histological low magnification shows dense spindle cells proliferation arranged in intersecting fascicles with scattered, isolated, thin, epithelial islands (a, Hematoxilyn-Eosin, 20x). High magnification emphasizes the epithelial neoplastic cells enveloped in a ring of mixoid substance inbetween the desmoplastic fascicles (b, Hematoxilyn-Eosin, 100x). Immunohistochemical staining for CKAE1/AE3 highlights the epithelial neoplastic strands compressed by the abundant collagen fibers (c, Hematoxilyn counterstain, 40x), while Bcl- 2 and CK 19 (d - e, Hematoxilyn counterstain, 100x): positive results in the epithelial neoplastic cells are rare, and very weak.