9 Pigmented Lesions
• Tattoo often appears on gingiva adjacent to amalgam restorations or crowns, but it may be on any surface and, in particular, after apicoectomy (root apex surgery) with amalgam retrofill (Fig. 9-1, A-C).
Silver within amalgam (combination of silver, mercury, tin, and other metals) stains agyrophilic reticulin fibers of connective tissue. It either leaches out of contacting amalgams or root canal fillings, or is traumatically implanted.
• Reticulin fibers, endomysium, and endoneurium may be stained golden-brown with no particulate deposits; larger particles often are found within foreign body granulomas (see Fig. 9-2, B-E; Figs. 9-3 and 9-4).
FIGURE 9-2 Amalgam tattoo. A, Pigmentation with dense scar. B, Staining of fibers and foreign body giant cell reaction. C, Reticulin fibers stain golden brown. D, Deposition of fine particles along fibers. E, Staining of endoneurium and vascular basement membrane.
• Coarse black granules of nonrefractile, slightly geometric, foreign material, some of which lie within multinucleated giant cells of foreign body granulomas; no distinguishing features so history important in diagnosis (Fig. 9-5)
• Particles are brown, spherical, uniform, only a few microns in diameter, and they tend to align in linear fashion between collagen fibers, although this may represent pigment within dendritic processes of macrophages; particles are often present within macrophages (Fig. 9-8, A-D).
• Staining is positive with Prussian blue for iron and Fontana-Masson for melanin, although degree of staining is variable (see Fig. 9-8, E); usually elicits no fibrosis or inflammation.
FIGURE 9-8 Quinacrine pigmentation. A, Slight acanthosis with no inflammation. B, Fine, dark brown pigment granules with no inflammation. C, Pigment granules are spherical and within macrophages or in linear array between collagen fibers. D, Pigment granules are in linear array, possibly within dendritic processes. E, Granules stain for iron (Prussian blue stain).
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Sloan P, Kujan O. Re: Martin TJM, Sharp I. Oral mucosal pigmentation secondary to treatment with mepacrine, with sparing of the denture bearing area. Br J Oral Maxillofac Surg. 2004;42:351-353. Br J Oral Maxillofac Surg. 2005;43:268
Treister NS, Magalnick D, Woo SB. Oral mucosal pigmentation secondary to minocycline therapy: report of two cases and a review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;97:718-725.
The two most common melanocytic lesions in the oral cavity are oral melanotic macule (comprising more than 80% of melanotic lesions) and postinflammatory hypermelanosis. Some melanotic macules are likely to represent end-stage postinflammatory hyperpigmentation. The less common melanoacanthosis also represents postinflammatory pigmentation.
Oral Melanotic Macule
• Increased melanin occurs within basal cells in the absence of or with minimal melanocytic hyperplasia; with incontinent melanin and melanophages in lamina propria; melanin is most prominent in the lower half of the epithelium and at tips of rete ridges (Figs. 9-11 and 9-12).