Pigmented lateral periodontal cyst: A case report and review of pigmented odontogenic cysts

Abstract

Pigmented odontogenic cysts are uncommon and to date, only 37 cases have been reported in the English literature. Here, we report a case of a pigmented lateral periodontal cyst (LPC) in the maxilla of a 48-year-old female. The patient presented with clinical swelling in the maxillary anterior region. Microscopic features of the biopsied specimen were consistent with a diagnosis of LPC. The epithelial cyst lining exhibited numerous coarse granules of melanin pigment, which was confirmed by S-100 immunohistochemistry and Fontana-Masson bleach histochemical method. Almost all documented cases of pigmented odontogenic cysts have occurred in Asians and African-Americans, with only three cases in white patients. Racial pigmentation may have a role in the pathogenesis of these lesions. Although the origin and pathologic significance of melanocytes in these pigmented intraosseous lesions cannot be explained, it may be something to consider for investigation in future.

Keywords: Fontana-Masson bleach; lateral periodontal cyst; melanin; pigmented odontogenic cysts.

Figure 1

Panoramic radiographic presentation of the pigmented lateral periodontal cyst shows a radiolucent lesion in the region of congenitally missing maxillary right central incisor (shown with red arrows). The cystic lesion grossly measured 1.5 cm × 1.3 cm × 0.8 cm

Figure 2

Histopathologic examination shows a thin epithelial lining and numerous localized thickened nodular plaques (a, H&E stain, ×100 for ×10 magnification). Brown–black granules interpreted as melanin noted within the lining epithelium and thickened nodular plaques (b, H&E stain, ×400 for ×40 magnification)

Figure 3

Histopathologic image shows a lining exhibiting numerous dark brown stained granules (a, H&E stain, ×400 for ×40 magnification). Fontana-Masson bleach shows the disappearance of brown granules in the tissue, confirming the pigment as melanin (b, H&E stain, ×400 for ×40 magnification)

Figure 4

Immunohistochemistry with S-100 shows a few cells in the epithelial lining to be positive for S-100 protein (a, IHC stain, ×200 for ×20 magnification). Few S-100-positive cells are seen in the lining and in superficial connective tissue subjacent to the lining, marked with blue arrows (b, IHC stain, ×400 for ×40 magnification)