Existing hypotheses are based on the fact that only the hands and feet are involved and posit the role of temperature differences, vascular anatomy, differences in the types of cells (rapidly dividing epidermal cells and eccrine glands).In the case of PPE caused by PLD, the following mechanism has been demonstrated: sweat deposits and spreads the drug on the skin surface; then the drug penetrates into the stratum corneum like an external agent; palms and soles have high density of sweat glands, and their stratum corneum is approximately 10 times thicker than the rest of the body, and becomes an efficient long-term reservoir for the penetrating PLD, which was deposited on the skin before. Diagnosis
Painful red swelling of the hands and feet in a patient receiving chemotherapy is usually enough to make the diagnosis. The problem can also arise in patients after bone marrow transplants, as the clinical and histologic features of PPE can be similar to cutaneous manifestations of acute (first three weeks) graft-versus-host disease. It is important to differentiate PPE, which is benign, from the more dangerous graft-versus-host disease. As time progresses, patients with graft-versus-host disease progress to have other body parts affected, while PPE is limited to hands and feet. Serial biopsies every 3 to 5 days can also be helpful in differentiating the two disorders. Prevention
The cooling of hands and feet during chemotherapy may help prevent PPE.
However, true prevalence of MR has not been confirmed yet. Types
Rhinitis is categorized into three types (although infectious rhinitis is typically regarded as a separate clinical entity due to its transient nature): (i) infectious rhinitis includes acute and chronic bacterial infections; (ii) nonallergic rhinitis includes vasomotor, idiopathic, hormonal, atrophic, occupational, and gustatory rhinitis, as well as rhinitis medicamentosa (rebound congestion); (iii) allergic rhinitis, triggered by pollen, mold, animal dander, dust, Balsam of Peru, and other inhaled allergens. Infectious
Rhinitis is commonly caused by a viral or bacterial infection, including the common cold, which is caused by Rhinoviruses, Coronaviruses, and influenza viruses, others caused by adenoviruses, human parainfluenza viruses, human respiratory syncytial virus, enteroviruses other than rhinoviruses, metapneumovirus, and measles virus, or bacterial sinusitis, which is commonly caused by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Symptoms of the common cold include rhinorrhea, sneezing, sore throat (pharyngitis), cough, congestion, and slight headache. Nonallergic rhinitis
Nonallergic rhinitis refers to rhinitis that is not due to an allergy. The category was formerly referred to as vasomotor rhinitis, as the first cause discovered was vasodilation due to an overactive parasympathetic nerve response. As additional causes were identified, additional types of nonallergic rhinitis were recognized. Vasomotor rhinitis is now included among these under the more general classification of nonallergic rhinitis. The diagnosis is made upon excluding allergic causes.