Lichen Scrofulosorum-Like Eruption Colocalizing to the BCG Site

To the Editor: The Bacillus Calmette-Guerin (BCG) vaccination protects against tuberculosis (TB)-related meningitis and disseminated TB. However, it can occasionally lead to various local and systemic reactions, though severe complications are rare. Local reactions include induration, blister formation, chronic discharging ulcers, lupus vulgaris, and regional lymphadenopathy, with or without suppurative drainage. Rarely reported cutaneous reactions include erythema nodosum, erythema multiforme, generalized maculopapular eruptions, exfoliative dermatitis, lichen scrofulosorum, lichen nitidus, and papulonecrotic tuberculid.1 Herein, we report a case of a 5-month-old infant presenting with a lichen scrofulosorum-like eruption localized to the BCG vaccination site. A 5-month-old female infant was accompanied by the mother to the pediatric dermatology outpatient department with a 2-month history of persistent skin lesions around the site of BCG vaccination on her left arm. The child had been vaccinated at birth, with an uneventful antenatal and perinatal history. There was no family history of tuberculosis or exposure to individuals with active TB. The infant's growth and development were appropriate for her age. Cutaneous examination revealed multiple, skin-colored to reddish, pinhead-sized follicular papules, some with fine scaling, localized around the BCG vaccination site (Fig. 1A), with a few papules scattered on the face and thighs. The mucocutaneous examination was otherwise unremarkable. Given the clinical morphology, a differential diagnosis of lichen scrofulosorum was considered. A skin biopsy from a follicular scaly papule around the BCG vaccination site revealed multiple ill-formed granulomas composed of epithelioid histiocyte aggregates in the superficial and deep dermis, along with Langhans-type multinucleated giant cells, suggestive of granulomatous inflammation consistent with a lichen scrofulosorum-like eruption (Figs. 2A–C). Special staining for acid-fast bacilli was negative. The tissue bit for GeneXpert was negative. Based on these findings, a diagnosis of a lichen scrofulosorum-like eruption after BCG vaccination was established. Chest x-ray was normal. The gastric aspirate for mycobacteria was noncontributory. The child was closely monitored without initiating antitubercular therapy. During a follow-up visit 3 weeks later, some papules showed partial self-resolution (Fig. 1B). The BCG vaccination scar remained well healed, and no new lesions were observed.FIGURE 1.: A, Multiple grouped red to skin colored pinhead-sized follicular papules, a few appearing scaly, on the arm clustered around the BCG scar site. B, Partial self-resolution of skin lesions after 3 weeks.FIGURE 2.: Histopathology showing multiple ill-formed granulomas composed of aggregates of epithelioid histiocytes in the superficial and deep dermis with the Langhans type of multinucleate giant cells (A) (Hematoxylin & Eosin, ×100) (B) (Hematoxylin & Eosin, ×200) (C) (Hematoxylin & Eosin, ×400).Lichen scrofulosorum is a rare cutaneous manifestation of tuberculosis, typically occurring in individuals with heightened tuberculin sensitivity. It is characterized by small, reddish-brown papules clustering around hair follicles, often on the trunk and extremities. The pathogenesis involves a delayed hypersensitivity reaction to Mycobacterium tuberculosis antigens, leading to perifollicular granulomatous inflammation.1,2 In this case, the development of a lichen scrofulosorum-like eruption 5 months after BCG vaccination, predominantly localized to the vaccination site, suggests a localized cutaneous reaction rather than systemic dissemination. This aligns with previous reports indicating that BCG vaccination can occasionally trigger dermatologic reactions, particularly in individuals predisposed to tuberculin hypersensitivity. According to Park et al,1 granulomas in lichen scrofulosorum after BCG vaccination may display a distinctive infiltration pattern involving hair follicles, distinguishing them from classical lichen scrofulosorum. Granulomas in lichen scrofulosorum are typically perifollicular and periadnexal. In this case, multiple granulomas were observed in the dermis, however, the morphology favored lichen scrofulosorum. The management of BCG vaccine-related lichen scrofulosorum primarily involves clinical observation and supportive care. In this instance, the decision not to initiate antitubercular therapy was based on the benign nature of the skin lesions and the absence of active tuberculosis. This case highlights a rare dermatologic complication after BCG vaccination in an infant, presenting as a lichen scrofulosorum-like eruption. Early diagnosis through clinical evaluation and histopathologic examination is crucial to ensure appropriate management and prevent unnecessary antitubercular treatment.