Primary Multi Drug Resistant Tuberculosis (MDR TB) Osteomyelitis in Sternum associated with Xeroderma Pigmentosa: A Case Report

Abstract

A rare autosomal recessive genetic disease, Xeroderma Pigmentosum (XP) starts in the childhood. Clinically, it develops as cutaneous photosensitivity and pigmentary changes in UV exposed areas of the body. DNA damage that is unrepaired and unresolved by the mutated XP genes leads to an increased risk of development of cancer. Continued exposure to UV radiation may lead to development of skin cancer. In 30% of XP patients, there is also development of neurological disorders with more chances for CNS neoplasms. Patients with XP have reduced interferon IFN-γ production, lower natural killer (NK) cell activation, and less circulating T cell numbers. These NK cells and T cells are important in preventing infection and neoplasm. The ratio of CD3+ to CD4+ circulating lymphocyte is reduced in XP. Studies have shown the role of an inhibitory serum factor to Phytohemagglutinin (PHA) stimulation in XP patients which might cause a serious hampering of the delayed hypersensitivity response. Activated macrophages are the main effector cells involved in the elimination of M. tuberculosis. This activation of macrophages is clearly led by lymphocyte products, mainly IFN-γ, and proinflammatory cytokines like TNF-α. Delayed hypersensitivity is a major mechanism of defense against many intracellular pathogenic organisms. These include mycobacteria, fungi, and certain parasites. Immunodeficiency in XP patients is not only associated with increased chances of neoplasms, but also increased susceptibility to infections like tuberculosis.