Sarcoidal granulomatous reaction on a scar post-microneedling: A case report

INTRODUCTION

Microneedling is a widely used dermatological procedure designed to enhance skin texture, reduce the appearance of scars, and promote skin rejuvenation through controlled micro-injuries to the dermis. It promotes collagen and elastin synthesis and is considered safe and minimally invasive.^[1]

Facial granulomatous reaction to microneedling is a rare complication, with 12 cases reported in the English language literature.^[1,2] Previously reported cases showed foreign body-type granulomas, while a recent case demonstrated sarcoidal-type granuloma on biopsy. Vitamin C and nickel from the needles have been postulated to act as an antigen that triggers the granulomatous reaction.^[1-3] This case report highlights that trauma, metal exposure, and immune dysregulation can trigger sarcoidal granulomatous reactions following microneedling, especially in scarred skin.

CASE REPORT

A 51-year-old Filipino female with no history of drug or cosmetic allergies presented with a red nodule overlying a scar on the right medial eyebrow that developed 2 weeks after using an 8-in-1 microneedling home device without medical supervision. No serum, cream, or other chemicals were applied to the treated area at any point before, during, or after the procedure. Following two microneedling sessions spaced 1 week apart, she noticed the appearance of a tender, red nodular plaque on her right medial eyebrow, which progressively increased in size. No systemic symptoms were noted on further history.

During her initial consultation, cutaneous examination revealed a 1.4 cm × 0.5 cm reddish-brown nodule on the right medial eyebrow [Figure 1a]. Polarized dermoscopic examination showed a central linear white area, orange translucent areas, fine white scaling, and linear and branching vessels [Figure 1b]. A 3-mm punch biopsy was performed, which revealed circumscribed nodular collections of epithelioid histiocytes surrounded by few lymphocytes in the dermis, reminiscent of a sarcoidal-type granulomatous reaction [Figure 2]. Tissue stains for fungi and mycobacteria were negative. No polarizable material was observed. Systemic work-up to rule out sarcoidosis was within normal limits.

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Figure 1:

(a) Baseline clinical photo and (b) dermoscopy showing orange translucent areas (black arrows), fine white scaling (white stars), linear and branching vessels (white arrows), and central linear white structures (black stars).

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Figure 2:

(a) Hematoxylin and eosin stain at ×40 magnification reveals circumscribed sarcoidal granulomas within the dermis (gray arrows), (b) consisting of epithelioid histiocytes (red arrows) and lymphocytes (blue arrows), which are further highlighted at ×200 magnification.

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The patient received two sessions of intralesional triamcinolone acetonide injections, administered 2 weeks apart. Each injection consisted of 0.2 mL of triamcinolone acetonide (10 mg/mL) diluted equally with lidocaine and injected 45° along the sides of the plaque using a gauge 32 needle. There was noted 50% flattening of the nodular plaque 2 weeks after the 1^st injection [Figure 3a] and 90% improvement with residual hyperpigmentation 2 weeks after the 2^nd injection [Figure 3b]. The lesion did not recur after 1 year of follow-up [Figure 3c]. Dermoscopic evaluation at one year [Figure 3d] revealed a linear white area with no visible blood vessels.

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Figure 3:

Follow-up photos during intralesional triamcinolone acetonide (TA) treatment: (a) 2 weeks after the 1^st TA injection, (b) 2 weeks after the 2^nd TA injection, (c) 1 year after the initial consult, and (d) dermoscopy after 1 year showing a linear white area (black stars) with no visible blood vessels.

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DISCUSSION

Microneedling is a common dermatologic procedure that involves creating controlled micro-injuries to the skin to stimulate collagen and elastin production, enhancing skin texture, and reducing scars.^[1] Although generally safe and minimally invasive, microneedling can sometimes lead to rare complications such as granulomatous reactions.^[1,2] This case contributes to the limited literature on granulomatous reactions associated with microneedling, specifically documenting a sarcoidal-type granuloma that developed following the unsupervised use of a home microneedling device.

Sarcoidal granulomatous reactions are characterized by aggregates of epithelioid histiocytes and are often triggered by infections and foreign bodies.^[3] In the context of microneedling, they may arise due to the introduction of foreign antigens or materials into the skin, such as Vitamin C or nickel from the needles, which have been reported as potential triggers in previous cases.^[1,2,4,5] A reported case of a cutaneous reaction following microneedling for post-acne scarring was attributed to nickel hypersensitivity – confirmed by patch testing and linked to nickel exposure from the device – and resolved with a 5-day course of oral prednisolone 30 mg daily followed by mild topical corticosteroids.^[4] In another report, a granulomatous reaction developed after microneedling combined with topical Vitamin C serum, initially managed with clobetasol 0.1% ointment twice daily for 6 weeks, along with intralesional injections of triamcinolone acetonide (5 mg/mL).^[1] Similarly, another report described a sarcoidal granulomatous reaction following microneedling with topical Vitamin C, initially treated with triamcinolone 0.1% ointment, with intralesional triamcinolone injections subsequently offered as a treatment option.^[2] Both patients were eventually lost to follow-up. It was suggested that the percutaneous introduction of Vitamin C through microneedling may have triggered an immune-mediated granulomatous response.^[1,2]

In our patient, no cosmeceuticals were used, and the sarcoidal granulomatous reaction is attributed to microneedling, likely triggered by nickel hypersensitivity or trauma-induced immune activation. Microneedling can provoke granuloma formation by exposing hidden antigens within scar tissue, a mechanism consistent with the concept of an immunocompromised cutaneous district (ICD) – areas of previously injured skin with acquired immune dysregulation that predispose to opportunistic conditions such as infections, tumors, and granulomatous disorders.^[6] By disrupting immune homeostasis in these vulnerable sites, microneedling may act as a triggering factor.

Scar sarcoidosis, a well-recognized form of cutaneous sarcoidosis, arises in inactive scars and has been associated with various traumas, including surgery, vaccinations, cosmetic tattoos, and herpes zoster infection.^[7] In this case, microneedling likely served as a similar traumatic stimulus, exposing concealed antigens or foreign substances such as nickel, which may have activated macrophages to release angiotensin-converting enzyme and lymphokines, leading to granuloma formation in line with the proposed pathogenic mechanisms.^[7] Nickel, in particular, may act as an antigen processed by macrophages and presented through human leukocyte antigen class II to CD4+ Th1 cells, initiating a cytokine cascade involving interleukin-2, interleukin-12, interferon-gamma, and tumor necrosis factor-alpha that contributes to granuloma development.^[3]

This immune activation parallels observations with pulsed dye laser (PDL) treatments, which have been reported to unmask previously sequestered antigens and trigger sarcoidal inflammation through vascular and immune pathways.^[8] Similar to PDL, microneedling on scar tissue may provoke a comparable granulomatous response. Although the precise mechanisms remain unclear, PDL has been noted to exacerbate sarcoidal lesions, likely due to a brisk immune reaction to confined antigens.^[8] Given that sarcoidosis fundamentally involves antigen presentation and granuloma formation, it is plausible that microneedling, like PDL, modulates the local immune cascade and triggers granulomatous inflammation in predisposed individuals. Larger studies, however, are needed to further elucidate these immunologic mechanisms and assess the safety of such procedures in patients with sarcoidosis.

Intralesional triamcinolone acetonide, a common treatment for cutaneous sarcoidosis,^[1,2] was effective in significantly reducing the lesion size, with sustained improvement and no recurrence after 1 year, demonstrating its efficacy for this rare complication.

CONCLUSION

This case underscores a rare but important complication of microneedling: A sarcoidal-type granulomatous reaction arising over scar tissue after unsupervised home use. In the absence of a cosmeceutical application, trauma or nickel hypersensitivity is suspected as the trigger, possibly involving immune dysregulation within an ICD. The report emphasizes the importance of recognizing granulomatous reactions as potential adverse effects of microneedling, especially in scarred skin. It also highlights the need for patient education on sterile technique and the value of professional supervision. Intralesional corticosteroids proved effective in achieving marked and sustained resolution of the lesion. Nonetheless, further research is warranted to elucidate the immunologic mechanisms underlying such reactions and to establish clearer safety protocols for the use of microneedling devices, particularly in patients with predisposing factors.