| Table 3-10 Common Foreign Body Reactions |
| | Foreign Body | | Clinical Findings | | Histological Reaction |
| | Intralesional corticosteroid | | Yellowish to skin-colored nodule at site of injection | | Foreign body granuloma with pale blue (mucin-like) acellular material in center |
| | Keratin | | Erythematous follicular papules
(i.e. acne keloidalis nuchae) | | Foreign body granuloma, ± fragments of keratin (section of hair shafts, birefringent) |
| | Suture material | | Erythematous papule or papules | | Birefringent basophilic suture fibers in dermis with surrounding foreign body granuloma |
| | Tattoo pigment | | Lichenoid papules, eczematous dermatitis, erythema or induration | | Extracellular pigment (typically black) with foreign body reaction (only if allergic reaction) |
| | Wood splinter | | Erythema, induration or papule | | Brownish color with prominent cell walls (honeycomb appearance) surrounded by granulomatous inflammation; birefringent |
| | Silica, zirconium, beryllium | | Erythema, induration or papule | | Foreign body granuloma, sarcoidal granuloma or caseating granuloma; doubly refractile spicules |
| | Silicone | | Nodule, indurated plaque, or ulceration | | ‘Swiss cheese’ appearance due to presence of silicone-filled cavities surrounded by histiocytes (may be multinucleated or foamy) |
| | Hyaluronic acid | | Erythema, induration, papule or nodule | | Basophilic amorphous material, stains with Alcian blue |
| | Paraffin | | Firm indurated nodule or plaque, ± ulceration | | ‘Swiss cheese’ appearance (stains with oil red O) |
| | Starch | | Indurated nodule typically | | Maltese cross configuration with polarized light |
| | Monsel’s solution | | Clinically consistent with nevus or tattoo | | Brown black deposits (containing iron) in dermis due to ferrous subsulfate |
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