Pilomatricoma, also known as pilomatrixoma or Malherbe’s calcified epithelioma, is a benign neoplasm originating from hair follicle matrix cells. Typically asymptomatic, these tumors are commonly found on the head, neck, and upper extremities. However, rare occurrences have been reported on the chest, trunk, or lower extremities. In recent years, there have been documented cases of pilomatricoma development following various immunizations, raising questions about potential associations between vaccinations and this benign tumor. This article presents a case of pilomatricoma that emerged at the site of a BNT162b2 mRNA COVID-19 vaccination and discusses the possible role of persistent inflammation in its development.
Case Presentation A 21-year-old healthy woman sought medical attention at our outpatient clinic due to an asymptomatic swelling on her left arm. Notably, she had received two doses of the BNT162b2 mRNA COVID-19 vaccine (Pfizer-Biontech) at the same site approximately one year and six months prior to her presentation. Furthermore, she reported experiencing an erythematous reaction at the injection site, which appeared two to three weeks after the second vaccine dose. Physical examination revealed a deeply palpable nodular lesion on the lateral side of her upper left arm, accompanied by soft, erythematous skin. (See Figure 1)
Figure 1 – Solid nodular lesion with overlying erythematous soft skin on the lateral side of upper left arm – Source – Pilomatricoma Growing at the SARS-CoV-2 mRNA Vaccination Site – Indian Journal of Dermatology68(5):588, Sep-Oct 2023.
Diagnosis and Histopathological Findings An excisional biopsy was performed, and the preliminary diagnosis was pilomatricoma, alongside a consideration of foreign-body granuloma. Histopathological analysis revealed a tumoral lesion within the deep dermis and subcutaneous tissue, characterized by centrally positioned large ghost cells with diffuse eosinophilic cytoplasm, multinucleated giant cells, and calcification. These findings confirmed the diagnosis of pilomatricoma, with no evidence of abnormal elastic fibers in the surrounding tissue, as demonstrated by a Verhoeff–van Gieson stain. The tumor was entirely excised, and no recurrence was observed during a ten-month follow-up period.
Discussion In the wake of widespread COVID-19 vaccination programs, various adverse reactions have been documented. These include local side effects like pain, erythema, and swelling, as well as exacerbation of pre-existing dermatological conditions, urticaria, morbilliform rash, pityriasis rosea-like eruption, purpura, herpes zoster, erythema multiforme, aphthae, and telogen effluvium. This article introduces the case of pilomatricoma as a potential local side effect of COVID-19 vaccination.
Pilomatricomas typically appear in children and adolescents as solitary tumors on the head or upper torso. Although the exact cause is not fully understood, they have been associated with trauma. There have been reports of pilomatricoma development following various vaccines and drug injections, with a strong female predominance. Interestingly, a recent publication also reported a case of pilomatricoma following BNT162b2 mRNA vaccination, similar to the case presented in this article.
Several theories have been proposed to explain the link between vaccine injections and pilomatricoma development. One hypothesis suggests that injection site injury or trauma may inhibit the apoptosis of damaged follicular epithelial cells, contributing to tumor formation. Additionally, persistent inflammation, wound healing processes, or the inoculated agents themselves may influence the development of pilomatricoma. Prior reports have discussed reactions such as ecchymosis, persistent vaccine reactions following BCG vaccination, and injection site reactions leading to severe erythema on the arm. The case presented here is consistent with these observations, as the patient reported erythema at the vaccination site 2–3 weeks after the second dose, likely a delayed-type localized hypersensitivity reaction attributed to vaccine excipients.
Conclusion This article presents a compelling case of pilomatricoma that potentially developed following SARS-CoV-2 mRNA vaccination. While a coincidental occurrence cannot be entirely ruled out, the growing body of similar reports suggests a potential association between mRNA vaccination and pilomatricoma development. However, further research is needed to elucidate the exact role of trauma and persistent inflammation in the pathogenesis of pilomatricoma. Given its rarity, pilomatricoma should be considered in the differential diagnosis of nodular lesions emerging at vaccination sites, especially in cases with a history of injection site reactions.
reference link : https://journals.lww.com/ijod/fulltext/2023/68050/pilomatricoma_growing_at_the_sars_cov_2_mrna.28.aspx
