# Pollen-Food Allergy Syndrome: Allergens, Clinical Insights, Diagnostic and Therapeutic Challenges
## 7 PFAS Diagnosis
### Skin Prick Testing (SPT)
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Category** & **Description** & **Details/Insights** \\ \hline
**Strengths** & & \\ \hline _Rapid results_ & SPT provides immediate feedback, allowing clinicians to correlate findings with the patient’s clinical history during the same visit. & Results are available within 15-20 min, making it an efficient diagnostic tool. \\ \hline _Minimally invasive_ & The test is simple, safe, and well-tolerated by most patients. & Requires only a small lancet and allergen extract, with minimal discomfort for the patient. \\ \hline _Broad applicability_ & SPT can assess sensitization to a wide range of pollens and foods in a single session, making it a comprehensive diagnostic tool for PFAS. & Ideal for identifying multiple allergens simultaneously, including pollens and related foods. \\ \hline _High sensitivity_ & When combined with fresh food testing, SPT achieves high sensitivity for detecting relevant allergens in PFAS. & Fresh food testing helps identify heat-labile proteins like PR-10 proteins and profilins not always detected by extracts. \\ \hline _Cost-effective_ & SPT is a relatively low-cost diagnostic tool compared to molecular diagnostics or in vitro IgE testing. & Widely available in clinical settings. \\ \hline \hline _Non-invasive follow-up_ & Enables ongoing monitoring of sensitization patterns without invasive procedures. & Can track allergen changes in response to therapy or environmental shifts. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Strengths and limitations of skin prick testing for PFAS [115; 187; 190; 194; 195; 196]. A negative SPT or specific IgE result is typically associated with high sensitivity and strong negative predictive value (NPV), making these tests essential tools for ruling out food allergies [98]. This is especially true when high-quality allergen extracts are used and the patient has no history of clinical reactions to the suspected food. However, these tests are not infallible, and their results must always be considered in the context of the patient's clinical history and overall presentation. Therefore, in patients with a strongly suggestive history of food allergy, a negative test result should not be relied upon to exclude the diagnosis outright [98]. Factors such as the age of the patient, the specific food allergen, and the presence of co-factors (e.g., exercise or alcohol) that might modulate allergic responses need to be taken into account [82]. The diagnostic performance of tests also varies depending on the allergen and the patient's age. For instance, younger children often have lower levels of allergen-specific IgE that still correlate with clinical allergy, while older individuals may show greater cross-reactivity due to conditions like pollen-food allergy syndrome. For example, peanut-specific IgE tests have been found to have higher specificity in younger children, whereas Ara h 2-specific IgE tests are more accurate in adults [197]. This difference may stem from the higher prevalence of primary peanut allergy in children compared to the greater occurrence of cross-reactive pollen-food allergy syndrome in older individuals [60]. Such variability underscores the importance of age-specific considerations when interpreting test results. Moreover, while diagnostic cutoffs for IgE levels or when sizes in SPT have been developed based on research studies and meta-analyses, these thresholds should not be applied rigidly in clinical practice [194; 197; 198]. They are better used as guidance to inform the likelihood of an allergy rather than as definitive decision points. Extrapolating cutoffs across different patient populations or clinical scenarios requires caution, as variations in local allergens, individual immune responses, and test protocols can influence diagnostic accuracy [98]. In summary, while negative SPT or specific IgE results are valuable for excluding food allergy in many cases, they are not absolute.