Resolution of Microneedling Associated Granulomatous Dermatitis with Oral Methotrexate

Microneedling, a minimally invasive procedure in which numerous epidermal and dermal microchannels are created through skin needling, has become a common and established treatment option for a plethora of dermatologic concerns, including skin rejuvenation, facial rhytides, and acne scarring. With studies supporting the efficacy of microneedling across many dermatologic applications as well as its minimal post-treatment recovery, this therapeutic option is generally well-regarded among both clinicians and patients. The limited side effects also augment its popularity with the most common - mild erythema, localized edema, and skin flaking - expected and self-resolving within 72 hours. However, microneedling is associated rarely with more concerning adverse effects. The procedure is disparate, including variable use of pre- and post-treatment topical cosmeceuticals, most of which aim to promote microneedling-induced wound healing and regeneration. With microneedling's creation of entry points into the skin, the possibility arises for development of an immune response to a penetrating material, whether from the needle or an antigenic topical agent. This adverse effect has been reported rarely in the literature with variable and not always favorable outcomes. We report a case of granulomatous dermatitis secondary to microneedling with almost complete resolution through use of oral methotrexate.