A case report and literature review: Factitious disorder imposed on another and malingering by proxy.

Factitious disorder imposed on another (FDIA) and malingering by proxy (MAL-BP) are two forms of underreported child maltreatment that should remain on physicians' differential. This case of a 2-year-old boy, which spans 6 years, reveals the complexity in and difficulties with diagnosis. Key features include the patient's mother using advanced medical jargon to report multiple disconnected concerns and visits to numerous providers. As a result, the patient underwent many investigations which often revealed normal findings. FDIA was suspected by the paediatrician, especially following corroboration with the child's day care and past primary health care provider. This case demonstrates the possible overlap in diagnoses, which are characterized by a lack of consistent presentation and deceitful caregivers, often complicated by true underlying illness. The authors use clinical experience and limited existing literature to empower paediatricians to confidently diagnose and report FDIA and MAL-BP to limit future harm to children.

Increased pain sensitivity and decreased opioid analgesia in T-cell-deficient mice and implications for sex differences.

The processing of pain in the central nervous system is now known to have an important immune component, including T cells of the adaptive immune system. T cells have been shown to release endogenous opioids, and although it is well known that opioids have effects on T-cell populations, very little attention has been given to the converse: how T cells may affect opioid regulation. We find here that, in addition to displaying significantly increased baseline pain sensitivity across various pain modalities, T-cell-deficient mice (CD-1 nude, Rag1 null mutant, and Cd4 null mutant) exhibit pronounced deficiencies in morphine inhibition of thermal or inflammatory pain. Nude mice are also deficient in endogenous opioid-mediated analgesia, exhibiting no stress-induced analgesia from restraint. The relevant T-cell subpopulation seems to be CD4 T cells because adoptive transfer of them but not CD8 cells into nude mice rescues both the pain and morphine analgesia phenotypes. As previously reported, we also observe a sex difference in CD-1 mice, with females requiring 2- to 3-fold more morphine than males to produce equal analgesia. Nude mice display no sex differences in morphine analgesia, and the sex difference is restored in nude mice of either sex receiving CD4 T cells from CD-1 donor male or female mice. These results suggest that CD4 T cells play an as yet unappreciated role in opioid analgesia and may be a driver of sex differences therein.