Brian S Hoyt1, Philip R Cohen2. 1. Department of Dermatology, University of Texas Medical School at Houston, Houston, Texas, United States. 2. Department of Dermatology, University of California San Diego, San Diego, California, United States. E-mail: mitehead@gmail.com.
Sir,We appreciate the erudite and insightful contribution of the authors regarding our manuscript on cutaneous metastases within a radiation port.[12] Furthermore, we concur with the excellent and relevant examples that were provided. Indeed, a variety of insults to the skin, including surgical scars, can result in a localized immunocompromised district.[3]In addition, we have noticed and acknowledged the immunocompromised district in three additional settings. A 75-year-old man underwent stereotactic radiation therapy for treatment of his non-small-cell lung cancer. He developed radiodermatitis which subsequently resolved completely. However, 3 months after completing his radiotherapy the patient developed biopsy-confirmed erythema multiforme localized within his radiation port. The lesions resolved with topical corticosteroids.[4]Graft-versus-host disease can also present within an immunocompromised district. A 74-year-old man with mantle cell lymphoma developed sclerotic cutaneous graft-versus-host disease following a second allogenic stem cell transplant. Interestingly, the sclerotic skin changes were localized to the waistband area. We suspect that the repeated physical trauma, pressure, and friction from the patient's pants and belt created an immunocompromised district, thus predisposing that area to the subsequent development of graft-versus-host disease.[5]Two patients were noted to have zosteriform Staphylococcus aureus infections localized to a distinct dermatome (T11-12 and T4, respectively). The presentation of Staphylococcus aureus in a dermatomal distribution had not been previously reported, and we suspect that these patients may have previously experienced subclinical herpetic infection. Thus, the dermatomal presentation of S. aureus would represent an example of Wolf's isotopic response. Alternatively, the lesions could in fact be following the lines of Blaschko, representing a congenital susceptibility to infection.[6]In conclusion, as the authors mentioned, physical injuries such as surgical scars,[3] as well as repeated friction or trauma,[4] ionizing radiation,[5] or burns,[7] can produce an immunocompromised district. Localized immunocompromised districts can also result from chronic lymphedema, herpetic infections, and vaccinations.[67] Therefore, in summary, a wide variety of cutaneous insults can produce localized immune dysregulation by affecting both lymphatic flow and neuromediator signaling. This can result in a blunted or heightened immune response.[7] Subsequently, dermatologic conditions, skin infections, or neoplasms (primary or metastatic) can occur in the cutaneous immunocompromised district.