| Domain | Key findings | Numeric details | Evidence type | Source year / DOI | Citation |
|---|---|---|---|---|---|
| Entity / classification | Polymorphous adenocarcinoma (PAC) is a malignant salivary gland tumor, predominantly of minor salivary glands, with morphologic diversity, infiltrative growth, and generally low metastatic potential; originally described as polymorphous low-grade adenocarcinoma and renamed by WHO to PAC to reflect a broader biologic spectrum including higher-grade variants. | Systematic review dataset: 409 PAC cases from 32 studies (1988-2021). | Systematic review / meta-analysis; narrative review | 2022, https://doi.org/10.1007/s12105-022-01453-6; 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000001, pqac-00000002) |
| Anatomy / clinical course | PAC arises mainly in minor salivary glands; diagnosis is often straightforward in the palate but can be difficult in uncommon sites such as the oropharynx, sinonasal tract, and nasopharynx. Clinical course is usually indolent/favorable, though aggressive behavior can occur. | Common-site emphasis: palate; uncommon sites specifically listed: oropharynx, sinonasal tract, nasopharynx. | Systematic review / meta-analysis; narrative review | 2022, https://doi.org/10.1007/s12105-022-01453-6; 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000001, pqac-00000003, pqac-00000002) |
| Pathology / IHC | Characteristic features include cytologic uniformity with architectural diversity, infiltrative borders/growth, and possible myxohyaline matrix. Helpful IHC profile: CK7+/CK20−, p63+/p40−, S100+, vimentin+, GFAP−; p63+/p40− is especially useful against adenoid cystic carcinoma. | Positive staining rates: pan-cytokeratin 97.3%, CK7 96.8%, CK7/8 97.4%, E-cadherin 90%, vimentin 92.5%, S100 97%, p63 91.7%, SOX10 100%; negative: CK20 0%, p40 0%, GFAP 5%; p63+/p40− in PAC 38/39 (97.4%) vs ACC 1/155 (0.006%); OR 801.32; mean MIB-1 labeling index 3.78%. | Systematic review / meta-analysis | 2022, https://doi.org/10.1007/s12105-022-01453-6 | (pqac-00000000, pqac-00000001, pqac-00000003) |
| Molecular genetics | PAC is associated with PRKD1 alterations on chromosome 14; the PRKD1 E710D hotspot mutation is highlighted as a useful ancillary diagnostic marker. PRKD-family signaling is linked to migration/differentiation through MAPK and RAS-related pathways. Cribriform adenocarcinoma has been incorporated into the PAC spectrum, although debate remains. | Specific retrieved numeric frequency not available in current evidence; hotspot named: PRKD1 E710D. | Narrative review | 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000002) |
| Diagnosis | Diagnosis remains morphology-based, with IHC and molecular testing as adjuncts. The most clinically important differential diagnosis is adenoid cystic carcinoma; p63+/p40− strongly favors PAC. FISH has shown reasonable success for detecting PRKD1 alterations. | Differential performance metric: OR 801.32 for p63+/p40− pattern distinguishing PAC from ACC; PAC 38/39 vs ACC 1/155. | Systematic review / meta-analysis; narrative review | 2022, https://doi.org/10.1007/s12105-022-01453-6; 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000000, pqac-00000001, pqac-00000002) |
| Treatment | Retrieved disease-specific evidence indicates correct diagnosis is clinically important because management differs from mimics; broader salivary gland review states surgical resection is principal treatment for most salivary gland neoplasms, with other modalities used according to behavior/stage. | No PAC-specific response-rate or regimen-level numeric outcomes available in retrieved evidence. | Systematic review commentary; narrative review | 2022, https://doi.org/10.1007/s12105-022-01453-6; 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000000, pqac-00000002) |
| Prognosis | PAC generally has a favorable prognosis, but regional and distant metastases can occur and may become difficult to control; WHO renaming reflects recognition that behavior is not uniformly “low grade.” | No survival percentage, recurrence rate, or metastasis rate captured in current retrieved evidence. | Systematic review / meta-analysis; narrative review | 2022, https://doi.org/10.1007/s12105-022-01453-6; 2021, https://doi.org/10.3390/cancers13153910 | (pqac-00000000, pqac-00000001, pqac-00000002) |
| Evidence gaps | Current retrieved evidence is strongest for classification, morphology, and IHC; it is comparatively weak for PAC-specific epidemiology, environmental risk factors, treatment algorithms, survival statistics, and modern omics/clinical-trial data. | Missing from retrieved evidence: incidence/prevalence, sex ratio, age distribution, survival %, recurrence %, metastatic %, prospective trials, validated biomarkers beyond diagnostic adjuncts. | Evidence synthesis gap assessment | Based on retrieved 2021-2022 evidence | (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000003) |


*Table: This table condenses the most relevant retrieved evidence on salivary gland polymorphous adenocarcinoma, emphasizing classification, diagnostic pathology, PRKD-related molecular findings, and where the current evidence remains limited.*