Ethmoid-Nasal Phosphaturic Mesenchymal Tumour

Abstract

Phosphaturic Mesenchymal Tumour (PMT) is a very rare benign neoplasm. Weinder and Santa Cruz first used the acronym PMT in 1987, due to the histological polymorphism shown by the neoplasm. About 95% of PMT involves bones and only 5% involves ENT districts. The clinical picture of PMT is characterized by TIO or tumour-induced osteomalacia, which causes bone pain, muscular weakness and pathological fractures and causes symptoms that can vary, depending on the location. The knowledge of the biological process of this rare neoplasm is therefore crucial to treat it. Due to its local aggressiveness, there is indication for a surgical resection with clean surgical margins. The surgical treatment firstly aims at reducing local aggressiveness, limiting the invasion to the adjacent structures, such as the base of the skull, orbit or palate and, as a consequence, the paraneoplastic syndrome induced by the tumour with its sequences. Most described PMT cases are benign, even though some episodes of malignant transformation with distance metastasis were registered.

Keywords: Phosphaturic mesenchymal tumour; Phosphaturia; Head and neck neoplasm; Sinonasal; TIO; paraneoplastic syndrome. The cases linked to head and neck district were stratified per location and the cases that involved other sections were not considered.

Clinical Case

Male patient, 53 years old, had been showing nasal obstruction for six months, otitis treated with inhaled antibiotics and crenotherapy with no results. He also reported paresthesia on left hard palate [1]. He underwent rhinoscopy with optical fibres showing evidence of a neoformation of the right nasal concha, basis right of the nasal cavity with subtotal occlusion of the right posterior nasal aperture which impeded to see the Eustachian tube orifice. A CT with contrast medium confirmed the presence of a neoformation with partial involvement of the right pterygopalatine fossa, delimited by a confining bone. As the neoformation was located, the patient underwent an endoscopic transnasal surgical removal of the neoformation. The histological result initially showed the neoformation as a pleomorphic adenoma of the right nasal cavity. After a revision of the slides in another centre a phosphaturic mesenchymal tumour was diagnosed, due to the histological polymorphism characterized by hyalinization with microcystic spaces and a prevalence of chondroid and myxochondroid pattern. Later, the patient underwent a revision of the surgery with enlargement of the surgical margins and with a completely negative histological result for the disease. Moreover the concentration of calcium, phosphatemia and phosphaturia excluded Tumour-Induced Osteomalacia (TIO). Today, after 8 months since the second surgery, the patient appears to be free from the disease.

Discussion

ETM PMTs are extremely rare. The diagnose is usually late due to the presence of osteomalacia or to symptoms linked to a local invasion [3]. Patients affected by paraneoplastic syndrome can show nonspecific bone pain, muscular weakness and pathological fractures [2- 5]. PMT doesn’t show to have any link with sex and emerges to affect a very ample range of patients, from the age of 3 to 73 [2-5]. 95% of PMTs were observed in bones and only 5% in craniofacial districts [2- 7]. Among these about 50% of tumours were found in the sinonasal tract [2-8]. In our revision it was observed that 20 cases of PMT reported in literature involve the sinonasal tract, while the rest of them involve other ETM tracts, as mandible, mouth, pharynx, larynx, thyroid and temporal bone [2-8]. From a histological point of view PMT is characterized by spindle-shaped or stellar cells in a myxochondroid or myxoid matrix with calcification [2-5]. Osteocytes in PMT are responsible for osteomalacia through the production of Fibroblast Grow Factor 23 (FGF23), which inhibits the transport of the sodium phosphate renal tubules leading to a phosphaturia and a consequent bone demineralization [9,10]. PMT is mostly suspected when a not familial hypophosphatemia is present. Diagnostic workup must take into consideration the patient’s history, an objective systemic exam and a search for localizations in arms and legs and ETM [10]. An otorhinolaryngologist who finds himself in front of a histological PMT must investigate a possible osteomalacia, as most cases see the presence of a paraneoplastic syndrome, and exclude the involvement of the bones [11]. In the series displayed in chart 1 it is possible to observe that only 6 patients didn’t present TIO. In an extensive revision carried out by Folpe et al. on 109 mesenchymal tumours on the extremities, only 3 cases didn’t present TIO [2]. The first line treatment is surgical resection with ample margins, which leads to a normalization of phosphatemia and phosphaturia with an improvement of the mineralization of bones [2]. The persistence of metabolic alterations after surgical resection is predictive of an incomplete surgical resection or a relapse [1]. Surgery appears to be the best choice also for the rare malignant manifestations of PMT, while adjuvant chemotherapeutic treatments haven’t been established, yet, due to the small amount of cases [12].

Results

From the revision of literature 405 articles containing PMT cases from 1970 to 2015 were selected.

36 ETM PMT cases were found, among those 20 localized on a nasal-sinusal level and 16 in other locations, such as mandible, base of the mouth, pharynx, larynx, thyroid and temporal bone (Table 1).

TABLECREATED

Table 1: Clinical pictures present in literature.