Melanin pigmented periradicular lesions of extracted teeth: a report of 3 cases and review of the literature.

This article reports 3 cases of melanin pigmented lesions among 75 histologically diagnosed periradicular lesions of extracted teeth. Case 1 was a 25-year old male who presented with one week history of toothache involving a tender carious left mandibular second molar tooth (37), with periapical radiolucency and diagnosed clinically as acute apical periodontitis. The lesion was diagnosed histologically (using Haematoxylin and Eosin) as periapical granuloma, while histochemical examination (using Masson-Fontana technique) showed the presence of round/oval shaped melanin pigmented macrophages (melanophage) in the lesion. Case 2 was a 54-year old male with one week history of toothache associated with tender carious right maxillary first molar tooth (16) with periapical radiolucency. A clinical diagnosis of acute apical periodontitis was made, but histological and histochemical examination showed a melanin pigmented periapical granuloma with spindle shaped melanophage. Case 3 was a 28-year old female who presented with 4 days history of toothache, involving the tender left mandibular first molar tooth (36). The lesion had periapical radiolucency and a clinical diagnosis of acute apical periodontitis. On examination histologically and histochemically, the lesion was diagnosed as an intraosseous melanocytic naevi with dark-brown nests of round naevus cells. In conclusion, this article shows the rarity of melanin pigmented periradicular lesions in the jaws. The cases reported suggest that the trigger for formation of melanin-pigmented cells in the periradicular lesions may be related to the acute phase of the lesions. Further study is recommended to determine if the remnants of the migratory neural crest cells are the precursors of melanin-pigmented cells in the periradicular region.