September 2019 HSC Section 1 Congenital and Pediatric Problems

ZAMANI ET AL .

T1/T2. High grade, high T-stage, and nodal involvement were uncom- mon in children with MEC, and none had distant metastases at diag- nosis. Note that minor SGCs are staged based on location accord- ing to the AJCC/UICC-cancer staging systems, but tumor sizes can still be compared with tumors of the major glands. AciCC, AdCC, and adenocarcinoma were uncommon in children and most studies did not provide information on tumor grade and stage for these tumor subtypes. Larger, multicentric studies with dedicated head and neck pathologists are needed to assess these tumor histological types in children. Although rare, AdCC has a much poorer long-term progno- sis than MEC, and lifelong follow-up is desirable for children with this histopathology. 4 Due to the rarity of these tumors in children, not much research has been made comparing different treatment modalities for children. Instead, surgeons choose to adopt the same treatment strategies used in adults, but with caution regarding adjuvant radiotherapy. Surgery was performed in almost all children with SGC, most of them receiv- ing primary surgery alone and one-fourth of children received adju- vant radiotherapy. This may be due to the easily accessible tumor sites, which due to their lower grade and stage required less adju- vant therapy. For children with parotid gland tumors, roughly half had partial parotidectomies, the other half had total parotidectomies, and the facial nerve was spared in most cases. In the present study, only three included studies evaluated surgical margins, with 10% ( n = 1/10), 15% ( n = 4/27), and 21% ( n = 9/42) of cases having positive surgical margins. 11,21,22 Perineural invasion was also only evaluated in three studies, with 8% ( n = 2/24), 16% ( n = 10/61), and 36% ( n = 6/16) of cases having perineural invasion. 16,22,23 The latter study by Galer et al (2012) only evaluated perineural invasion in 16 of 35 included minor SGCs, and all six children with perineural invasion had AdCCs. 22 Regarding complications, a common short-term complication to parotid surgery was temporary facial nerve palsy. 18,25 The facial nerve may be more sensitive to dissection and traction in children, causing a temporary palsy. 18 Some studies noted that persistent facial nerve paralysis was more common when total parotidectomy was performed. 25,32 In these children, the nerve should be reconstructed if possible. Long-term complications to parotid surgery include facial numbness and Frey syndrome, but sufficient data were not available to quantify the rate of complications. 20,23,25 In the included studies in this review, neck dissections were performed in one-third of children. Neck dissection in children with SGC is controversial, since most children do not have nodal involvement, as seen in the study by Kupfermann et al that reported only 17% positive lymph nodes in neck dissected children. 5 Regarding recurrences, one-fifth of the children had salivary gland tumor recurrences. The studies did not define when a tumor was considered a recurrence or a residual cancer. One study found that high-grade SGCs in children were more likely to have a recurrence and have a higher mortality. 27 A few studies also noted that tumor enucleations typically led to recurrence. 7,16,17,33 Cockerill et al noted that 10 of 14 local recurrences occurred after initial tumor enucle- ations and in children where neck dissection was not performed. 17 Tumor enucleation or excision biopsies should be avoided due to the possibility of tumor seeding. 5 Two studies found that tumors with

Histological distribution of salivary gland cancer among

F I GURE 2

children aged 0–19 years ( n = 565). (A) Parotid gland, (B) submandibular gland and (C) minor salivary glands. The distribution of “other” cancer types in the salivary glands with frequencies < 3% are outlined in Supporting Information Table S3. NOS, not otherwise specified sections may ensure that a proper histological diagnosis is made. Another important consideration is that there may occur cancers of nonsalivary gland origin in these locations (such as rhabdomyosarco- mas or lymphomas), and the diagnosis of SGC is, therefore, not clear prior to surgery. The most common histological type of SGC in children was MEC, which was mostly low/intermediate grade of differentiation and stage

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