Cephalosporins are one of the most commonly prescribed classes of antibiotics. Immediate IgE-mediated hypersensitivity reactions have been reported with use of a specific cephalosporin, as a cross-reaction between different cephalosporins or as a cross-reaction to other β-lactam antibiotics, namely, penicillin. Historically, frequent reports of anaphylaxis following administration of first- and second-generation cephalosporins to patients with a history of penicillin allergy led to the belief of a high degree of allergic cross-reactivity. More recent evidence reveals a significantly lower risk of cross-reactivity between penicillins and the newer-generation cephalosporins. The current thought is that a shared side chain, rather than the β-lactam ring structure, is the determining factor in immunologic cross-reactivity. Understanding the chemical structure of these agents has allowed us to identify the allergenic determinants for penicillin; however, the exact allergenic determinants of cephalosporins are less well understood. For this reason, standardized diagnostic skin testing is not available for cephalosporins as it is for penicillin. Nevertheless, skin testing to the cephalosporin in question, using a nonirritating concentration, provides additional information, which can further guide the work-up of a patient suspected of having an allergy to that drug. Together, the history and the skin test results can assist the allergist in the decision to recommend continued drug avoidance or to perform a graded challenge versus an induction of tolerance procedure.

A 42-year-old woman, who is a member of a military parachute team, presents with more than 10 years of nasal congestion, facial pressure, and headaches that she has been self-treating with over-the-counter decongestants. She has a history of polypectomy in 1991 for similar symptoms, but did not have otolaryngology follow-up after the surgery. Following the surgery, she had a 5-year hiatus from parachuting, during which time she was asymptomatic. However, when she returned to parachuting in 1997, she had the gradual return of nasal congestion, facial pressure, and headaches. In addition to her sinus symptoms, the patient has a history of ocular and nasal pruritis and frequent sneezing when she is exposed to grass or dust, most prominent during the summer months. She grew up on a farm in Iowa and had intermittent ocular allergy symptoms when she was bailing hay. She has never had a formal allergy evaluation. The patient has no personal or family history of other atopic disease, such as asthma, atopic dermatitis, or food allergies. Examination revealed an athletic-appearing woman with a protuberance at the superior medial aspect of her right orbit that was evident on external inspection. Her nasal membranes were boggy, and bilateral nasal polyps were visible by rhinoscopy. Sinus CT scan revealed complete opacifi cation of the right frontal sinus with bony erosion posterior. Laboratory evaluation included an elevated IgE of 1870 ng/mL, normal spirometry, and positive skin prick testing to multiple tree pollens, grasses, and weeds. Skin prick testing was negative to Aspergillus fumigatus, Alternaria tenuis, Curvularia specifera, Helminthosporium iter, Mucor racemosus, and Penicillium notatum, but was positive to Cladosporium mix. Intradermal testing to A. fumigatus was positive. Her otolaryngologist identifi ed signifi cant polyp disease during endoscopic sinus surgery in the ethmoid region, obstructing her frontal sinus, as well as thick drainage in the frontal sinus consistent with eosinophilic allergic mucin. Surgical pathology revealed an alternating pattern of mucin and cellular debris rich in eosinophils. Special stains were positive for fungal elements. Culture of the drainage isolated Curvularia species. Expert Commentary: Dr. James T. LiAlthough chronic rhinosinusitis is one of the most common outpatient medical problems, the clinical evidence supporting the diagnosis and management of rhinosinusitis syndromes is rather slim. Nonetheless, patients such as the one presented here deserve our best shot at diagnosis and our best clinical judgment on therapeutic options.The diagnostic considerations of this case include nasal polyposis, chronic rhinosinusitis, allergic rhinitis, and allergic fungal sinusitis. This patient clearly has nasal polyposis based on the previous polypectomy (likely supported by histopathology), physical examination, and endoscopic sinus surgery. The sinus CT fi ndings and the eosinophils noted on surgical pathology support this diagnosis. The protuberance on physical examination and the b...