Journal of Clinical and Aesthetic Dermatology

APR 2018

An evidence-based, peer-reviewed journal for practicing clinicians in the field of dermatology

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26 JCAD JOURNAL OF CLINICAL AND AESTHETIC DERMATOLOGY April 2018 • Volume 11 • Number 4 C A S E R E P O R T DISCUSSION Amyloidosis is an extracellular deposition of fibrous protein either involving multiple organs or single areas of tissue. 4 Amyloid, a cross-beta supersecondary structure that is deposited in tissues, results from the conversion of peptides or proteins from their soluble functional states into highly organized fibrillar aggregates. 5 This is a complex process involving key players from the intracellular protein quality control system, extracellular chaperones and matrix components, proteases, and other cofactors. 6 In localized amyloidosis, the deposition of amyloid can be seen in the brain in the form of neurodegenerative disorders and in the skin as primary cutaneous amyloidosis. 2 Various neurodegenerative disorders that have been documented include Alzheimer's disease, Parkinson's disease, and amyotropic lateral sclerosis. Primary localized cutaneous amyloidoses can present as lichen, macular, or nodular amyloidosis. In our patient, Alzheimer's disease was concurrently present with macular amyloidosis. In this case report, we have tried to summarize the pieces of evidence that can be helpful in attempting to determine whether there is any link between skin and brain amyloidosis. Due to the paucity of data regarding this correlation, there is a need for further exploration. Alzheimer's disease is clinically characterized by a progressive and gradual decline in cognitive function and neuropathologically characterized by the presence of neurofibrillary tangles and senile plaques. 7 Diabetes is a risk factor for Alzheimer's disease. Macular amyloidosis is clinically characterized by small, brownish macules with a characteristic reticulated or rippled pattern. 4 In a study performed by Krishna et al, 8 the interscapular area, one of the areas affected in our patient, was identified as the most common site of involvement. Additionally, Bandhlish et al 4 concluded in their study that sun-exposed sites, such as the face and extremities affected in our case, are more commonly involved in macular amyloidosis. Histopathologically, aggregates of homogeneous and eosinophilic dermal deposits are seen. On staining with Congo red, under polarized light, apple green birefringence is observed. 9 In the brain, beta amyloid deposits are seen initially in the parahippocampal region and later in the limbic system. 3 A study done by Clos et al 2 revealed that there might be a connection between the cutaneous form of amyloidosis and neurodegenerative amyloidosis. Amyloid deposits in the brain and skin share a common ultrastructure and pathogenic mechanism. The cross-seeding mechanism in the skin that leads to amyloid deposits in the brain through a misfolded form of α-synuclein indicates that the presence of amyloidogenic material outside the brain can have a direct impact on neurodegenerative amyloidosis. 2 A specific amyloidogenic peptide sequence has been identified in the skin and brain. Furthermore, the basic pathogenic mechanisms for skin and brain amyloidopathy seem to be similar. 3 Schreml et al 3 have shown in their study that genes such as presenilin-1 and ApoE4 FIGURE 1. Macules forming diffuse reticulate patterns of pigmentation on the patient's extremities FIGURE 2. Dermoscopic findings: "white central hub" (black arrow), "radiating streaks" (red arrow)

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