An Unexpected Post-Egg-Free Influenza Vaccine Granulomatous Reaction.

ABSTRACT: A 53-year-old woman presented with a pruritic plaque on the left upper arm that appeared following an egg-free flu vaccine due to a history of reaction to the standard vaccine. The affected area enlarged over a several month period immediately following vaccine administration. Physical examination revealed an 8 × 4 cm coalescent pink plaque on the left upper arm. A shave biopsy of the lesion showed dermal "naked" granulomas, or granulomas with sparse lymphocytic infiltrate at the margins, as typically seen in sarcoidosis. No foreign material was seen in the granulomatous reaction, including with polarization. Special stains, including acid fast bacilli, Grocott methenamine silver, periodic acid-Schiff, and Gram, were negative for organisms. The diagnosis of granulomatous dermatitis was made. Subsequent imaging demonstrated no findings suggestive of sarcoidosis. While vaccine-associated hypersensitivity reactions occur frequently, these reactions are typically due to individual vaccine components, such as egg protein, and do not normally result in the formulation of granulomas. Vaccination-induced granulomas are more often associated with the use of aluminum as an adjuvant; however, this is not present in the egg-free influenza vaccine. Thus, a granulomatous reaction to the egg-free influenza vaccine is very unusual and, to our knowledge, not previously reported.

Myxoid perineurioma: an entity with many mimics.

We present a case of a female patient who presented with a 0.6cm flesh-colored "rubbery" papule on the left thigh. Biopsy revealed a dermal myxoid tumor containing spindled cells, tapered nuclei, indistinct cell borders, and a large number of mast cells. The spindle cells stained negative for S100 protein and Sox10 on immunohistochemistry, excluding myxoid neurofibroma, but positive for epithelial membrane antigen (EMA), and CD34, supporting a diagnosis of myxoid perineurioma. Interestingly, the mast cells showed cytoplasmic and nuclear positivity for microphthalmia transcription factor (MiTF). The lesion was fully excised one year later with identical histopathology and ancillary immunohistochemical profile.