Eruptive Milia Within a Tattoo: A Case Report and Review of the Literature

The most frequently reported tattoo-related dermatoses, according to a study of 234 tattooed patients, are allergic,¹ infectious,^2,3 and granulomatous^4,5 reactions occurring in 2.1% of this population.⁶ Less common reactions are lichenoid,⁷ photoallergic,⁸ pseudolymphomatous,⁹ discoid lupus erythematosus,¹⁰ incidental skin neoplasm,¹¹ and koebnerization of psoriasis.^12,13Milia within tattoos are rare, with only three reports in the English literature (Table 1). This case is used to illustrate relevant findings, discuss the proposed pathogenesis and review treatment options.

A 19-year-old African American female with no past medical history presented with new white papules arising within a tattoo on the left upper chest, shoulder, and arm. Lesions appeared one month after tattoo placement, which was inked six months prior to presentation. Prior to the visit, the patient had tried over the counter antibiotic ointment with no improvement. She denied pruritus, pain, bleeding, or other symptoms. Aside from tattoo placement, there was no trauma to the site. She denied use of other topical or systemic medications.On physical examination there were multiple, minute, firm, monomorphic, white papules arising within various pigments of the tattoo (Figure 1). Lesions were confined within the margins of the tattoo, sparing adjacent skin (Figure 2). Similar findings were absent from her other tattoos.A punch biopsy of a lesion on the left shoulder demonstrated deposits of black granular material in the dermis and small, infundibular cysts containing cornified cells (Figures 3 and 4). There were no signs of a primary inflammatory process. Periodic Acid-Schiff stain was negative for hyphae (Figures 3 to 5).Daily urea 40% cream was prescribed with significant reduction in size and number of milia. Upon follow-up, her treatment regimen was supplemented with tretinoin 0.1% cream.

Tattoos serve both religious and aesthetic decorative purposes. Previously, tattoos were associated with regimented and marginalized groups, however, increasing popularity over the last two decades has made them mainstream.¹⁴Clinically, milia within tattoos present as small, yellowish papules within tattoo pigments. There is no accompanying history of trauma and the lesions can appear at any time following inking. While the condition can be pruritic, patients are mostly asymptomatic and typically present weeks-to-months following placement of the tattoo. However, milia have also even been reported within a longstanding tattoo, appearing in the setting of a lichenoid reaction to red ink.¹⁵Histopathologically, milia in tattoos are characterized small keratinized cysts lined by stratified squamous epithelium with keratin arranged in concentric lamellae.16 Pigment is found within macrophages and extracellularly in the dermis. Inflammation and spongiosis are absent.The pathogenesis of eruptive milia is incompletely understood, although it is most likely due to trauma. Generally, milia are