Urushiol, which is not itself a protein, acts as a hapten and chemically reacts with, binds to, and changes the shape of integral membrane proteins on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a T-cell-mediated immune response. Of these poisonous plants, sumac is the most virulent. The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, papules, vesicles, blisters, and streaking.Estimates vary on the percentage of the population that will have an immune system response. Approximately 25 percent of the population will have a strong allergic response to urushiol. In general, approximately 80 percent to 90 percent of adults will develop a rash if they are exposed to .0050 milligrams (7.7×10−5 gr) of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction. Genetics
Allergic diseases are strongly familial: identical twins are likely to have the same allergic diseases about 70% of the time; the same allergy occurs about 40% of the time in non-identical twins. Allergic parents are more likely to have allergic children, and those childrens allergies are likely to be more severe than those in children of non-allergic parents. Some allergies, however, are not consistent along genealogies; parents who are allergic to peanuts may have children who are allergic to ragweed.
Like follicular carcinoma, unilateral hemithyroidectomy is performed for non-invasive disease, and total thyroidectomy for invasive disease. Diagnosis
It is difficult to correctly diagnose follicular neoplasms (FNs) on fine-needle aspiration cytology (FNAC) because it shares many cytological features with other mimicking lesions. Classification
It is impossible to distinguish between follicular adenoma and  carcinoma on cytological grounds. If fine needle aspiration cytology (FNAC) suggests follicular neoplasm, thyroid lobectomy should be performed to establish the histopathological diagnosis. Features sine qua non for the diagnosis of follicular carcinoma are capsular invasion and vascular invasion by tumor cells. Still, focuses of the capsular invasion should be carefully evaluated and discriminated from the capsular rupture due to FNA penetration resulting in WHAFFT (worrisome histologic alterations following FNA of thyroid). Follicular carcinoma tends to metastasize to lung and bone via the bloodstream. Papillary thyroid carcinoma commonly metastasizes to cervical lymph nodes.HMGA2 has been proposed as a marker to identify malignant tumors. Treatment
Treatment is usually surgical, followed by radioiodine. Initial treatment
If follicular cells are found on cytological testing, it is common to carry out hemithyroidectomy to distinguish between follicular adenoma and follicular carcinoma on histopathological examination, proceeding to completion thyroidectomy and postoperative radioiodine ablation where carcinoma is confirmed. This way total thyroidectomy is not carried out unnecessarily. Thyroidectomy is invariably followed by radioiodine treatment at levels from 50 to 200 millicuries following two weeks of a low iodine diet (LID). Occasionally treatment must be repeated if annual scans indicate remaining cancerous tissue.