Phosphaturic mesenchymal tumors show positive staining for somatostatin receptor 2A (SSTR2A).
Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome associated with tumors that secrete phosphaturic hormones, most notably fibroblast growth factor 23 (FGF23). The majority of tumors associated with this syndrome show stereotypical histological features and are now known as phosphaturic mesenchymal tumors (PMTs). We postulated that immunohistochemistry for somatostatin receptor 2A (SSTR2A) could be used to definitively identify PMTs or other tumors that cause TIO. Immunohistochemistry for FGF23 and SSTR2A was performed on 15 tumors from 14 patients with a definite diagnosis of TIO. All showed positive staining for both markers. While FGF23 staining was quite focal in some tumors, SSTR2A showed diffuse strong expression. In 40 control tumors not known to be associated with the clinical or biochemical features of TIO, FGF23 expression was found in 2 cases (one aneurysmal bone cyst and one osteosarcoma). SSTR2A expression was found in 9 control tumors (4 synovial sarcomas, 2 hemangiomas, 2 aneurysmal bone cysts and one osteosarcoma). Only one tumor (an aneurysmal bone cyst) showed positive staining for both FGF23 and SSTR2A. SSTR2A also commonly stained neoplastic and non-neoplastic endothelial cells. We conclude that neither FGF23 nor SSTR2A expression are specific for the diagnosis of PMT. However both stains are highly sensitive. Because of its diffuse strong expression and widespread availability, immunohistochemistry for SSTR2A is useful to confirm the diagnosis of PMT in an appropriate setting particularly if material is limited. Negative staining can serve as an excellent rule out test for this diagnosis.
Sydney Medical School, University of Sydney, Sydney, 2006 Australia; Cancer Diagnosis and Pathology Group, Northern Translational Cancer Research Unit, Kolling Institute of Medical Research, St Leonards, 2065 Australia; Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards, 2065 Australia; Departement de Biopathologie, Centre Leon Berard, 69373 Lyon France. Electronic address: replymh@leyoti.com.au.
Michelle
M
Houang
Adele
A
Clarkson
Loretta
L
Sioson
Marianne S
MS
Elston
Roderick J
RJ
Clifton-Bligh
Michael
M
Dray
Dominique
D
Ranchere-Vince
Anne-Valerie
AV
Decouvelaere
Arnaud
A
de la Fouchardiere
Anthony J
AJ
Gill
D000328:Adult; D004365:Drugs, Chinese Herbal; D028001:Eleutherococcus; D005260:Female; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008637:Mesenchymoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009372:Neoplasms, Connective Tissue / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D010018:Osteomalacia / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D010257:Paraneoplastic Syndromes / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D017481:Receptors, Somatostatin / Q000378:metabolism*
D004365:Drugs, Chinese Herbal; C000717427:FGF23 protein, human; D017481:Receptors, Somatostatin; C106140:somatostatin receptor sst2A; D000089703:Fibroblast Growth Factor-23; C400150:Acanthopanax gracilistylus, extract
FGF 23; Gallium-68 DOTATATE PET/CT; Phosphaturic mesenchymal tumor; SSTR2A; Tumor-induced osteomalacia