The Diagnostic Challenges of Low Grade and High Grade Tubo-Ovarian Serous Carcinomas W Glenn McCluggage Belfast, Northern Ireland
Enterprise Interest None
OVARIAN SEROUS CARCINOMA (OSC) RECENT DEVELOPMENTS two distinct tumour types (called low grade and high grade OSC) (WHO 2014) not two grades of same neoplasm different neoplasms with different underlying pathogenesis, molecular events, behaviour, prognosis high grade much more common than low grade (approx 18-19:1) use instead of traditional grading schemes
PATHOGENESIS (LOW GRADE SEROUS) low grade arise from pre-existing benign and borderline tumour (probably not all cases) micropapillary variant of serous borderline may be intermediate stage in development of low grade serous carcinoma well-defined adenoma-carcinoma sequence
PATHOGENESIS (HIGH GRADE SEROUS) traditionally thought to arise directly from ovarian surface epithelium or epithelium of cortical inclusion cysts; now clear that most cases arise from epithelium of distal fallopian tube precursor lesion is serous tubal intraepithelial carcinoma (STIC) doesn t arise from borderline tumour
MORPHOLOGY classification as high grade or low grade serous is reproducible (MD Anderson system) distinction based mainly on nuclear atypia (not on architecture) in worst area of tumour BUT low grade serous uniform nuclei with mild atypia; < 12 mitoses per 10 HPFs; usually approximately 2/10 HPFs; no necrosis or multinucleation high grade serous moderate to marked atypia; >12 mitoses per 10 HPFs; often necrosis and multinucleate cells
HIGH GRADE SEROUS CARCINOMA- MORPHOLOGIC DIVERSITY Papillary/ micropapillary Slit-like Glandular Microglandular/ microcystic Cystic Solid Multinucleate cells Signet ring cells Blue appearance Oncocytic/ clear cell OFTEN ADMIXTURE OF PATTERNS
PSEUDOENDOMETRIOID
CLEAR CELL CHANGE IN SEROUS CARCINOMA (SOMETIMES POSTCHEMOTHERAPY)
TRANSITIONAL- LIKE
SOLID- UNDIFFERENTIATED AREAS
OVARIAN HIGH GRADE SEROUS CARCINOMA
WT1 in PSEUDOENDOMETRIOID AREAS IN HIGH GRADE SEROUS CARCINOMA
WT1 in CLEAR CELL AREAS IN HIGH GRADE SEROUS CARCINOMA p53 WT1
WT1 IN TRANSITIONAL-LIKE AREAS IN HIGH GRADE SEROUS CARCINOMA
UNDIFFERENTIATED OVARIAN CARCINOMA WT1
MORPHOLOGY OF BRCA ASSOCIATED HIGH GRADE SEROUS CARCINOMAS SET pattern (Solid, pseudoendometrioid, Transitional) Higher mitoses; more geographical necrosis? Increased tumour intraepithelial T lymphocytes Different patterns of metastatic disease ( pushing rather than infiltrative ) Similarities to breast carcinomas in BRCA ALL PATIENTS WITH HGSC SHOULD UNDERGO GERMLINE BRCA TESTING- FUNDING QUESTIONS
MIXED OVARIAN CARCINOMAS historically quite common (up to 10-20%) most commonly historically reported were mixed serous/ endometrioid; mixed serous/clear cell; mixed serous/undifferentiated; mixed serous/transitional (mostly variants of high grade serous carcinoma- doubtful if these combinations exist) occasionally get mixed endometrioid/ clear cell (association with endometriosis) occasionally others CATEGORY OF MIXED CARCINOMA DROPPED FROM WHO 2014 CATEGORY OF TRANSITIONAL CARCINOMA ALSO DROPPED FROM WHO 2014
Mixed Ovarian Carcinomas Improved recognition of types has virtually abolished mixed tumours 15 of 871 cases reviewed (1.7%) by H/E using modern diagnostic criteria 22 cases thought to be mixed were investigated further by immunohistochemistry and molecular testing Only 13 true mixed carcinomas when immunohistochemistry and molecular data incorporated Mixed carcinomas account for less than 1% of ovarian carcinomas Mackenzie et al. Am J Surg Pathol 2015; 39: 1548-1557
MARKERS IN HGSC WT1- good marker of serous carcinomas (extrauterine)- low grade and high grade (occasional low grade endometrioid adenocarcinomas positive) (approximately 5% HGSCs negative) p16- about two thirds of HGSCs block - type positivity (other morphological types patchy) p53 (about 95% mutation-type ) ER (positive 70-80%) PAX8, CA125, CK7 positive HMGA2, IMP3 often positive
p53 p53 immunohistochemistry- lot of confusion only consider positive/significant if diffuse strong nuclear immunoreactivity (75-80% cells suggested- associated with missence mutation) p53 null consistent with serous carcinoma (different type of mutation (nonsense) or deletion resulting in truncated protein which is not detected by immunohistochemistry) third pattern of mutation-type staining- cytoplasmic (rare pattern) most normal tissues and tumours exhibit focal, weak, heterogenous staining ( wild-type staining) (usually <50%) (about 5% of HGSCs with Tp53 mutation exhibit wild-type staining) DON T REPORT AS POSITIVE OR NEGATIVE- REPORT AS WILD- TYPE / NORMAL or MUTATION-TYPE /ABERRANT OCCASIONALLY DIFFICULT TO INTERPRET ( wild-type at upper end; negative mutation-type versus wild-type )
Interpretation of p53 immunohistochemistry No TP53 mutation Normal Wild type pattern Nonsynonymous =missense Stopgain Indel Splicing Stopgain Indel Splicing p53 overexpression p53 complete absence p53 cytoplasmic abnormal; mutation-type J Pathol Clin Res 2016;2:247
2016: www.thebagp/resources
p16 IN OVARIAN/ TUBAL (and uterine) HIGH GRADE SEROUS CARCINOMA Diffusely positive in most cases (Modern Pathology 2014; 27; 991-1001) Low grade serous, endometrioid, clear cell, mucinousfocally positive Approximately 2/3 homogeneous; 1/3 heterogeneous TMA- 115 HGSC (49 heterogenous; 63 homogenous) In stage I- III cases, homogeneous p16 worse prognosis (OS- significantly better with heterogenous stainingp=0.0367) (Histopathology 2016;68;615-618)
LOW GRADE SEROUS CARCINOMA Management may differ significantly from HGSC Surgery much more likely No chemotherapy for early stage No chemotherapy for advanced stage in some places (if totally debulked) Targetted therapies Specific trials Invasive implants in association with ovarian serous borderline tumour (extraovarian low grade serous carcinoma) (sometimes looks invasive in nodes in association with serous borderline in ovary)
LOW GRADE SEROUS- MORPHOLOGIC DIVERSITY Papillary/ micropapillary Glandular Solid Mucinous areas Clefts Often numerous psammoma bodies (psammocarcinoma is a low grade serous carcinoma with abundant psammoma bodies)
Psammocarcinoma- LGSC with many psammoma bodies
MARKERS IN LGSC WT1- good marker of serous carcinomas (extrauterine)- low grade and high grade (occasional low grade endometrioid adenocarcinomas positive) (approximately 5% HGSCs negative) p16- patchy positivity p53 ( wild-type )- ALWAYS ER (positive >90%); PR (usually, but not always, positive) PAX8, CA125, CK7 positive
WT1
p53
CLINICAL BEHAVIOUR- LGSC and HGSC LGSC (mean 52) younger than HGSC (mean 62) HGSC poor prognosis (usually presents at advanced stage, responds well initially to chemo but usually recurs; occasional long term survivors) LGSC more indolent (good prognosis for early stage; advanced stage- patients usually die of tumour) (IJGP 2013; 32; 529-535- stage 2-4, <30% survival at 10 years; not significantly different to HGSC); (AJSP 2016;40;627-635; 5 year survival 62.3% LGSC, 43.9% HGSC but no survival difference at 10 years)
DISTINCTION BETWEEN LOW GRADE AND HIGH GRADE SEROUS CARCINOMA Usually straightforward Occasionally difficult (especially in small biopsies) Rarely get admixtures (transformation low grade into high grade) Only reliable marker is p53
p53 high grade serous carcinomas 95% mutationtype staining low grade serous exhibit wild-type staining
HIGH GRADE SEROUS MIMICKING LOW GRADE p53
LOW GRADE OSC WITH BIGGER NUCLEI
LOW GRADE OSC
p53
TRANSFORMATION LOW GRADE INTO HIGH GRADE rare (AJSP 2012; 36; 368-375) (serous borderline or low grade serous carcinoma) can be misdiagnosed (bigger nuclei in low grade serous) can transform to HGSC, anaplastic carcinoma, carcinosarcoma p53 NOT reliable in such cases (may not be TP53 mutated)
TRADITIONAL VIEW OF PATHOGENESIS OF HIGH GRADE SEROUS CARCINOMA traditionally thought to arise directly from ovarian surface epithelium (OSE) or epithelium of cortical inclusion cysts thought that some cases might arise from secondary Mullerian system doesn t arise from borderline tumour
IS TUBAL FIMBRIA THE ORIGIN OF EXTRAUTERINE HIGH GRADE SEROUS CARCINOMA? proposal that tubal fimbria (distal tube) (secretory cells) is site of origin of many/most extrauterine high grade serous carcinomas (ovary, peritoneum and fallopian tube)
INITIAL EVIDENCE came from prophylactic risk reducing salpingooophorectomy specimens (RRSO) (BRCA1/2) once tubes were examined in their entirety, tubal lesions (distal) were seen with little/ nothing in ovary tubal lesions may be STIC (serous tubal intraepithelial carcinoma) or small HGSCs now well established in BRCA patients that tube is origin of HGSCs? does same hold true for sporadic HGSCs
p53 in STIC
WHAT ABOUT SPORADIC HGSCs Usually present at advanced stage Tube (s) often obliterated and embedded in tubo-ovarian mass Difficult to study precursor lesions STIC/ mucosal HGSC found in carefully sectioned tubes (when both visible) in significant percentage of cases (up to twothirds) of sporadic HGSC
Implications for specimen handling SEE-FIM protocol ESSENTIAL for identifying STIC/early tubal involvement- now routinely done in tubo-ovarian HGSC
? FIELD-EFFECT IN HGSC same TP53 mutations in HGSC at multiple sites evidence that clonally related and not part of field-effect no evidence of field-effect in HGSC one site is primary with metastasis to the others other molecular evidence- common clonal ancestry at multiple sites
BUT IS TUBAL LESION PRIMARY OR METASTATIC? Intramucosal metastasis from a variety of sites may occur in tubes and mimic an in-situ lesion Gynaecological or non-gynaecological tumours when spread to tube exhibit mucosal involvement and even mimic STIC (AJSP 2015;39;35-51) Some molecular evidence that tube is initial site but difficult to prove by molecular techniques RECENT OBSERVATIONAL STUDIES PROVIDE FIRM EVIDENCE
USC INVOLVING FALLOPIAN TUBE WT1
HPV RELATED CERVICAL ADENOCA INVOLVING TUBE
INCIDENTAL SPORADIC HIGH GRADE SEROUS CARCINOMA established that incidental tumours in patients with BRCA1/2 mutation are of tubal origin 3 papers recently published- unsuspected STIC/ HGSC incidentally detected (ours= AJSP 2015; 39; 357-364) PROVES that sporadic HGSC of tubal origin (FINAL PIECE OF EVIDENCE)
Summary of findings of incidental HGSC in a non-prophylactic setting Study Total Cases Invasive Invasive Organ- Organ- Organ- cases with HGSC HGSC in confined confined: confined: STIC in tube ovary Disease tube ovary (tube OR ovary) Rabban, 2014 4 4 3 1 3 3 0 Morrison, 2014 22 22 6 1 21 21 0 Gilks, 2014 21 20 12 2 18 18 0 Total 47 47 22 4 43 43 0
EXTRAUTERINE HIGH GRADE SEROUS CARCINOMA- SITE OF ORIGIN FIGO 2014- same staging system (ovary, tube, peritoneum, undesignated) FIGO 2014 and WHO 2014- no recommendations regarding designating site of origin WHO- the decision as to primary site should be pragmatic, based on experience and professional judgement DOMINANT MASS THEORY TRADITIONALLY USED (ovary designated as primary site in most cases) possibilities- pelvic high grade serous; extrauterine; Mullerian; tubo-ovarian; undesignated implications:- epidemiology, tumour incidence/mortality, cancer registries, entry into clinical trials different viewpoints- STIC/ in situ criteria; dominant mass criteria
Ovarian? Peritoneal? Tubal? Undesignated?. CHAOS!
SURVEY: INTERNATIONAL JOURNAL OF GYNECOLOGICAL PATHOLOGY PMID 27801755 173 respondents Widespread acceptance of tubal origin (86% pathologists, 92% clinicians) Clinicians thought it more important to correctly assign a primary site than pathologists (71% versus 49%)
PROPOSAL FOR DESIGNATING SITE OF ORIGIN OF HGSC extensive examination of tube (SEE-FIM) any STIC or mucosal serous ca in tube- tubal origin if fallopian tube or fimbria not identified (obliterated by mass)- tubal origin ovarian primary if tumour in ovary and nothing in mucosa of tube (STIC or invasive) (both tubes need to be clearly visible and examined by SEE-FIM protocol) primary peritoneal- nothing in tube or ovary (vanishingly rare- will likely disappear) (WHO 2014) post-chemo (if no residual) or on small biopsy- designate as tubo-ovarian USING THESE CRITERIA- approximately 80% tubal primaries undesignated- very small proportion (Histopathology 2014; 65; 149-154; Gynecological Oncology 2016;141;195-198; International Journal of Gynecological Pathology 2016;35;230-237) CRITERIA ADOPTED BY ICCR site assignment is reproducible using these criteria
Summary of site assignment guidelines proposals Criteria Primary site Comment STIC present Fallopian tube Regardless of presence and size of ovarian and peritoneal disease Invasive mucosal carcinoma in tube, with or without STIC Distal end or entire tube incorporated into ovarian mass No STIC or invasive mucosal carcinoma in either tube in presence of ovarian mass Both tubes and both ovaries grossly and microscopically normal or involved by benign process in presence of peritoneal HGSC Fallopian tube Fallopian tube Ovary Primary peritoneal HGSC Regardless of presence and size of ovarian and peritoneal disease Regardless of presence and size of ovarian and peritoneal disease Regardless of presence and size of peritoneal disease As recommended in WHO blue book 2014 57
RETROSPECTIVE (n=151) PROSPECTIVE (n=111) Primary site T O P U T O P U Chemo 63 16 0 1 44 9 0 0 naive (79%) (20%) (0%) (1%) (83%) (17%) (0%) (0%) Post- 48 16 7 0 44 7 4 3 NACT (68%) (22%) (10%) (0%) (76%) (12%) (7%) (5%) Singh et al, 2015
Basis for tubal assignment in 44 chemonaive cases Criterion Number (%) STIC only 5 (11%) Invasive mucosal +/- STIC 26 (59%) Entire tube or part of tube incorporated in mass 13 (30%) Total 44
Unilateral vs bilateral tubal and ovarian involvement in HGSC Unilateral Bilateral Total Ovary 18 (38%) 29 (62%) 47 Fallopian tube 37 (84%) 7 (16%) 44 Bilaterality = strong indicator of secondary spread In 53 chemo-naïve cases, ovarian involvement in HGSC was significantly more frequently bilateral Tubal involvement unilateral in 84% supporting primary rather than metastatic involvement Singh et al, 2015
CONCLUSIONS Majority of extrauterine HGSC, hereditary and sporadic, arise in the fallopian tube, mostly its fimbrial end Multiple sites of HGSC arise from a single ancestral clone Molecular evidence does not support the concept of multifocal origin Primary peritoneal HGSC can only be diagnosed if both tubes and both ovaries show no STIC/HGSC Following a defined protocol results in reproducible site assignment Thus assigned, sporadic HGSC shows a similar site distribution to hereditary cases Witnessing a major paradigm shift