PACK syndrome: A case series and review.

A rare overlap syndrome between CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) syndrome and primary biliary cholangitis (PBC) is described as PACK syndrome, an acronym for primary biliary cholangitis, anticentromere antibodies, CREST syndrome, and keratoconjunctivitis sicca. In this retrospective cohort analysis and review, we present fourteen patients who meet diagnostic criteria for PACK syndrome in one of the largest case series of this group. All patients were female, 86% of whom were White with an average age of 66.7 years (range 39-78 years). The prevalence was 5.08% in our PBC cohort (n=256) similar to previous findings. CREST syndrome was diagnosed prior to PBC in 58% of our patients and limited pulmonary and renal involvement were observed. This syndrome is rare, but given its insidious development, clinicians should be aware of this potential overlap in CREST-only and PBC-only patients.