The Carney triad (CT) is gastrointestinal stromal tumor (GIST), paraganglioma, and pulmonary chondroma. The GISTs of CT show different clinical, molecular, and morphologic features to usual adult GISTs but are similar to the majority of pediatric GISTs. We postulated that these GISTs would show negative staining for succinate dehydrogenase B (SDHB). We performed SDHB immunohistochemistry on GISTs arising in 5 individuals with CT, 1 child, 7 individuals with GIST in young adulthood including 2 with germline KIT mutations, 3 individuals with neurofibromatosis 1, one 63-year-old female with multifocal gastric epithelioid GIST with lymph node metastases, and 104 consecutive unselected individuals with apparently sporadic GIST. The GISTs and paragangliomas arising in CT, the pediatric GIST, and the multifocal gastric GIST from the 63-year-old showed negative SDHB staining. GISTs from the 7 young adults and 3 with neurofibromatosis were SDHB positive. Of the unselected GISTs, 101 (97%) were positive. One of the negative GISTs arose in a 48-year-old female with previous recurrent multifocal gastric GISTs and the other 2 arose in females also in their 40s with gastric GISTs with epithelioid morphology. We conclude that negative staining for SDHB is characteristic of the GISTs of CT and the subgroup of pediatric GISTs which it resembles. Furthermore, when negative staining occurs in apparently sporadic GISTs in adults, the GISTs show morphologic and clinical features similar to pediatric and CT type GISTs. GISTs may therefore be divided into type 1 (SDHB positive) and type 2 (SDHB negative) subtypes.
*Department of Anatomical Pathology, Royal North Shore Hospital
¶Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital
††Cancer Genetics, Hormones and Cancer Group, Kolling Institute of Medical Research
‡‡Department of Endocrine Surgery, University of Sydney, Royal North Shore Hospital
†University of Sydney
∥Department of Anatomical Pathology, SEALS, Prince of Wales Hospital
♯Department of Medical Oncology, Prince of Wales Hospital
**Department of Medicine, University of New South Wales, Sydney
‡Department of Anatomical Pathology, John Hunter Hospital and University of Newcastle, Newcastle
§Department of Anatomical Pathology, ACT Pathology, Canberra Hospital, Garran ACT
§§PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.D.E.B. and R.J.C-B. contributed equally to this work
Correspondence: Anthony J. Gill, FRCPA, Department of Anatomical Pathology, Royal North Shore Hospital, Pacific Highway St Leonards, New South Wales 2065, Australia (e-mail: firstname.lastname@example.org).