Granular Cell Ameloblastoma: Retrospective Clinical and Histopathological Findings of Case Series and Review of Literature

Case Series

Austin J Dent. 2018; 5(5): 1118.

Granular Cell Ameloblastoma: Retrospective Clinical and Histopathological Findings of Case Series and Review of Literature

Hoyos AM*, Teshima THN, Dias CD, Pinto CAL, Coutinho-Camillo CM and Lourenço SV

Department of Stomatology, University of Sao Paulo, Brazil

*Corresponding author: Ana Maria HoyosCadavid, Department of Stomatology, School of Dentistry, Av. Prof Lineu Prestes 2227, University of Sao Paulo, Sao Paulo, Brazil

Received: September 05, 2018; Accepted: October 09, 2018; Published: October 16, 2018


Granular Cell Ameloblastoma (GCA) is classified as an unusual histological subtype of solid/multicystic ameloblastoma, characterized by granular changes of stellate-like cells located within the inner portion of epithelial follicles. Studies have revealed that cytoplasmatic granularity is caused by lysosomal overload; however, the mechanism involved remains poorly understood. Here we report eight cases of granular cell ameloblastoma, in the posterior region of the mandible. The age of the patients included in this case series ranges between 35 -64 years old, and 87.5% occurred in non-Caucasians, with a slight gender predilection for men (62.5%). There was no evidence of recurrence and the majority of the cases were treated with surgical resection (87.5%). All tumors displayed histopathological features consistent with the diagnosis of granular cell tumor.

Keywords: Ameloblastoma; Odontogenic Tumors; Pathology

Clinical Relevance

This paper presents the clinical and histopathological findings of eight cases of granular cell ameloblastoma, which is a rare tumor that represents only 3-5% of all ameloblastomas and predisposes to important risk of recurrence.


Odontogenic tumors comprise a complex group of lesions of diverse histopathological subtypes and clinical behavior, which can originate from tissue remnants of tooth formation. Ameloblastoma is a true neoplasm that particularly rises from the enamel organ type tissue with a slow growth pattern, although with infiltrative and recurrent potential, and it corresponds to the second most common odontogenic tumor (11%) [1,2]. This lesion is usually found almost exclusively in the lower jaw, near the angle of the mandible, and occur more often between the third and fifth decades of life [1,3].

According to the clinical and radiographic features, ameloblastomas are classified into conventional solid or multicystic, extra osseous or peripheral, desmoplastic and unicystic types [4].They can display distinctive histological findings mainly characterized by the presence of cystic areas composed of peripheral columnar cells in a palisaded basal cell layer that surrounds hyper chromatic granular cells. There are six histological variants known as follicular, plexiform (most common subtypes), acanthomatous, desmoplastic, granular and basal cell [3,4].

Granular cell ameloblastoma (GCA) is a rare type of ameloblastoma that represents only 3-5 % of all histological subtypes. GCA is mostly found as a combination of different histological patterns, particularly the follicular variant [1,5].This tumor was first observed and described by Krompecher in 1918 when it was named as pseudo xanthomatous cells [1,2]. It appears to be aggressive in nature, with a marked propensity for recurrence and can progress to metastasis [2,6].

Histologically, GCA is characterized by the presence of granular cells, which are usually small structures of around 1μm compared to rare giant granular cells that are up to 30μm. These cells appear typically within the central area of ameloblastic tumor follicles, progressively replacing the stellate reticulum, which may also extend to the peripheral columnar or cuboidal cells [2]. The granular cell shape can vary from the most common round to cuboidal, columnar or angular, in which the nuclei are pyknotic and hyper chromatic and the cytoplasm is filled with acidophilic granules, identified as lysosomal aggregates [2,7]. The presence of granular cells represents either a transitional or a matured stage in the life cycle of ameloblastomas. They start as normal stellate reticulum like cells, lead to the production of cytoplasmic granules and finally follow towards tissue degeneration and formation of cystic areas [5].

The current treatment for GCA is similar to other subtypes of ameloblastomas, in which radical surgical methods and accurate preoperative diagnosis. Regular follow-up management is recommended as conservative treatments as enucleation or curettage exhibit high recurrence rate [2]. Previous studies suggest that GCA represents more aggressive lesions, whereas others propose that GCA is just a transitional phase during the pathological course of ameloblastomas, therefore not requiring special attention [1,2].

The prognosis of GCA is considered favorable when early treatment is performed; however recurrence rate of over 30% has already been reported, implying potential unknown aggressive behavior of GCA [8]. A proper regular follow-up is therefore recommended, as recurrence has been shown to happen up to eight years after the initial treatment [1,2]. The uncertain clinical behavior reported for this type of ameloblastoma emphasizes the importance of better understanding its pathogenesis and clinical impact, and this article therefore aims to report the clinical and histological features of a retrospective case series of eight mandibular GCA.

Case Series

Given that GCA represents a rare pathological entity and that there are only few reports in the literature comparing their clinical and histopathological characteristics, a retrospective study of eight patients was performed. Clinical, demographic and histopathological data of all GCA diagnosed in the Department of Pathological Anatomy of the Hospital AC Camargo Cancer Center, SP Brazil, from 1953 to 2001, were evaluated according to the approval of the Ethics Committee In Research of the Faculty of Dentistry of the University of São Paulo - USP (protocol number 171/08;FR-216880).

The clinical features of all patients were obtained from their medical records, which include age, ethnicity, gender, and location of the lesion, treatment, and recurrence, radiographic and histopathological findings, shown in (Table 1). This retrospective analysis of GCA case series included eight patients ranging from 35 to 64 years old (average age of 46.8 years) with a slight predilection for men (62.5%) and for non-Caucasians (87.5%). The majority of the cases were treated with surgical resection (87.5%) that presented no evidence of recurrence, provided with a follow-up of more than 3 years. All GCA included in this study was found at the posterior region of the mandible particularly near the angle, with a multilocular radiographic pattern.

Citation: Hoyos AM, Teshima THN, Dias CD, Pinto CAL, Coutinho-Camillo CM and Lourenço SV. Granular Cell Ameloblastoma: Retrospective Clinical and Histopathological Findings of Case Series and Review of Literature. Austin J Dent. 2018; 5(5): 1118.