Paraganglioma Biobank

As shown in figure 1, for each of 146 consenting patients, we obtained primary tumor matched with blood and any normal tissue (nerves, vessels, skin, fibromuscular, connective tissue and bone) removed from the neck and base of the skull and for some cases adipose tissue from abdomen. Moreover, from some cases under trans-labirinthine vestibular surgery we sampled the Jacobson’s nerve that could represent a normal tissue of origin of head and neck PGL (HNPGL).

Biobank samples for each case are collected, preserved and analyzed as follows:

GLA: glutaraldehyde; PFA: paraformaldehyde; EM: electron microscopy; IEM: immuno electron microscopy; IHC: immunohistochemistry; RISH: rapid in situ hybridization

All 146 prospectively collected PGLs, together with a retrospective series of about 200 cases, are available in formalin-fixed, paraffin-embedded blocks.

The biobank includes also 100 PGL-derived xenografts (snap frozen, FFPE and 2.5% GLA for electron microscopy). Furthermore, 39 primary PGL cell cultures obtained from fresh collected samples are maintained in vapor phase liquid nitrogen freezer. Four primary cultures were immortalized by retroviral-mediated transduction of full-length hTERT and/or simian virus 40 (SV40) large-tumour (LT) antigen.

The biological samples in the research biobank are from 146 head and neck PGL patients recruited between 2009 and 2019 including 84 tympano-jugular, 32 tympanic, 11 carotid body, 9 vagal and other 10 cases are under classification and temporarily listed as PGL "not otherwise specified" (nos). One case had lymph node metastases, one case had two independent tumors (carotid body and vagal), 9 patients presented recurrency. For all cases preoperative urinary and plasma catecholamines were negative, in agreement with the mostly parasympathetic (non secretory) origin of head and neck paragangliomas. Only two patients reported a family history of paraganglioma. The overall mean age at surgery of the patients is 48 (range: 12-83) years old. Tympanic PGLs are associated in our series with higher age of the patients (mean: 56.3 yo), significantly different from the age of the patients with tympano-jugular (mean: 45 yo, P= 0,0002), vagal (mean: 41.6 yo, P=0,0025) and carotid body (mean: 48 yo, P=0.038) PGLs (Table 1).

Table 1: Sites of tumor origin, age and sex of the 146 PGLs of the series (column at left). SDHx germline mutation status in a subset of 109 PGL (column at center). SDHB immunohistochemistry (IHC) in a subset of 74 PGL of the series (column at right). The comparatively high frequencies of tympanic and tympano-jugular PGLs reflects recruitment at a specialized skull base surgery center. NA: not available.

Up to now, 109 out of 146 cases are characterized for germline point mutations and large deletions/rearrangements in the SDHA, SDHB, SDHC, SDHD, SDHAF2 and TMEM27 genes, in collaboration with Dr. Schiavi at Familial Cancer and Oncoendocrinology Unit - Veneto Institute of Oncology IRCCS. Somatic mutations and loss of heterozygosity analyses are ongoing on all cases. SDHB is affected by germline mutations in 16 cases (14,7%), followed in order by SDHC (8 cases, 7.3%), SDHD (6 cases, 5.5%), SDHA (4 cases, 3.9%), SDHAF2 (2, 1,8%) and TMEM127 (1 case, 0.9%), with an overall percentage of carriers equal to 34% compared to 66% of noncarriers (Table 1 and Table 2).

Table 2. SDHx status, age and sex of 109 patients screened for mutations and tumor-associated SDHB protein loss in a subset of 74 mutation carriers and noncarriers.