This case was reported in a literature article and described the occurrence of vesiculo-bullous eruption in a 12-month-old female subject who was vaccinated with DTPA, HIB, MMR and pneumonia 11-valent protein d conjugate vaccine. Subject's medical history included (on day 3 of live) seizure and rash. At 5 days of age she had again both symptoms therefore she was brought to the Emergency room. The cutaneous eruption, (of numerous discrete), were described as erythematous papules and vesicles which began on her face and progressed to her extremities, trunk and scalp. A Tzanck preparation was negative for multinucleated giant cells. Skin biopsy revealed mild focal spongiosis with scattered exocytosis of eosinophils in the lower epidermis and at the dermal ? epidermal junction. A mild dermal infiltrate composed of eosinophils and lymphocytes was also observable. Scattered dyskeratotic keratinocytes with eosinophilic hyaline cytoplasm were present within the epidermis. During the hospital course, diffuse, bilateral patchy hypo densities were demonstrated on head CT, suggesting encephalitis. She was given Phenobarbital for new onset seizures and empirically placed on ceftaxime, ampicillin and acyclovir. Blood, urine and cerebrospinal fluid cultures were negative for bacteria and viruses, including HSV. MRI demonstrated embolic-appearing infarcts, possibly accounting for these seizures. Subsequent thrombotic work-up was normal, and Electroencephalogram revealed no significant anomalies. The patient was discharged with a diagnosis of erythema toxicum neonatorum. One month after discharge, vesicobullous eruption recurred, but spontaneously resolved after 1 week. Similar eruptions occurred again at 4 months of age, presenting as discrete erythematous pustules and vesicles, in linear distributions, on the forearms and posterior legs. This particular eruption occurred prior to the patient receiving her 4-month immunizations. As these resolved, hypopigmented, atrophic linear streaks began to surface on the posterior legs and forearms, corresponding to the site of previous lesions. In light of her first biopsy, seizure medical history, and family history (patient's mother had a history of three miscarriages of unknown aetiology); the patient was given a presumptive diagnosis of Incontinentia Pigmenti. Genetic testing confirmed the diagnosis, demonstrating a mutation in nuclear factor (NF) -jB essential modulator (NEMO). No verrucous lesions were observed and no significant triggers or events occurred prior to these eruptions. One week after her 12-month vaccinations with unspecified dose of HIB vaccine (unknown), unspecified dose of MMR vaccine (unknown), unspecified dose of Pneumonia 11-valent protein D conjugate vaccine; the subject presented vesiculobullous lesions within these linear patches. Three to 5 days after her 18-month vaccinations with unspecified dose of DTPA (unknown), a similar eruption occurred in the same distribution. In neither of these cases, verrucous lesions, fever or other systemic complaints were reported. Additionally between these vaccinations she had two upper respiratory infections (URI) with fever, but without associated cutaneous eruptions. An ophthalmologic examination found no abnormalities, and the subject's mother reported no eruptions following vaccinations at 2, 4 and 6 months. A biopsy was performed. However, histopathology revealed vesicobullous IP, demonstrating florid changes consisting of eosinophilic spongiosis with pronounced eosinophilic exocytosis, multiple dyskeratotic keratinocytes, and a brisk perivascular chronic inflammatory infiltrate of eosinophils and lymphocytes in the dermis. The subject experienced late reactivation of the vesicobullous stage of IP, triggered twice by routine immunization at 12 and 18 months of age. According to the author the temporal association of vesicobullous eruption at 12 months and 18 months, along with absence of reported fever, an immunization-triggered vesicobullous reactivation seems likely. This case was medically significant by GSK.