BOTs: evolving concepts, evolving diagnostic criteria

evolving concepts + evolving diagnostic criteria = my evolving confusion

But bear with me; this is a v helpful review article, published in December 2016.

Based on a review of existing data (i.e. published literature), Hauptmann and colleagues have reviewed all the best-available-data about BOTs.  They make some helpful conclusions, and relate existing data with the the recent 2014 World Health Organization (WHO) Classification of Tumours of the Female Genital Organs; this includes some changes in terminologies to try (try!) to help with removing confusion about BOTs…… 

 I’ll leave you to decide if this is less confusing or not.

The current 2014 WHO Classification of Tumours of the Female Genital Organs uses the term “borderline tumor” interchangeable with “atypical proliferative tumor”—a terminology that was discouraged in the previous WHO classification [4], whereas the previously advocated synonym “tumor of low malignant potential” is no longer recommended [5].

(My) Highlights (NB – I’ve focused on SBOTs for now but there is lots in there about all types of BOTs.

What does the WHO say?

• The term ‘tumour of low malignant potential (LMP)’ is not recommended
• BOT is used interchangeably with ‘atypical proliferative tumour’ [which is stupid – the previous WHO classification discouraged this]

BOT is many things

• There are SIX subtypes: 
• Most are serous (50%) or mucinous (45%)
• Some are less common:
• endometrioid, clear cell, seromucinous,
  and borderline Brenner tumor

Although the distinction of serous or mucinous BOT from frankly
malignant tumors with destructive stromal invasion does not usually pose a
diagnostic problem, BOT can be associated with microinvasion, intraepithelial
carcinoma, lymph node involvement, and non-invasive peritoneal implants [7] and
establishing the correct diagnosis can be challenging in these cases. 

The diagnostic criteria are less well defined for the uncommon
histologic subtypes and sometimes hampered by subjectivity. 

The distinction of BOT from its benign adenomatous counterparts is
equally important, and overdiagnosis should be avoided, since it has important
clinical implications regarding staging and follow-up. 

What are SBOTs?

• Under the microscope, serous BOTs (SBOTs) have similar properties to low grade serous carcinoma (LGSC), i.e. to grade 1 ‘typical’ OC: this is why ensuring correct pathological diagnosis is so important
• Some evidence that SBOTs are precursors to LGSC; some evidence that they’re not

SBOTs and implants:
introducing new names [it’s
like learning a new language that keeps changing]

• Non-invasive implants + micropapillary pattern are now known as non-invasive
  low grade serous carcinoma (non-invasive LGSC)
• Invasive
  implants – invasive peritoneal disease – now
  known as low grade serous carcinoma (LGSC)
• For some of us (including me) –
  depending upon our time of diagnosis – this may change how our diagnosis is
  explained [very common for disease classification to evolve over time as our
  understanding increases]
• In July 2014, I was diagnosed as stage
  2c SBOT with micropapillary architecture, and with non-invasive implants.
• In the 1990s, this would have been
  called “non-invasive micropapillary (low grade) serous carcinoma”.
• These newer, 2014, guidelines change
  this to “stage 2c SBOT with micropapillary variant/non-invasive low grade serous carcinoma”.  
• It changes neither my
  prognosis nor my treatment plan but it helps with better understanding of how
  this disease works.

Microinvasion

• Microinvasion is not consistently associated with recurrence or poorer prognosis but the latest evidences hows no association between presence of microinvasion, recurrence and prognosis
• Also: “a higher rate of microinvasion has been observed in SBT diagnosed during pregnancy, suggesting possible influence by hormonal factors”.

Micropapillary pattern

• Presence of micropapillary pattern alone is not associated with prognosis (i.e. likelihood of recurrence, survival not affected)
• Where micropapillary pattern AND invasive peritoneal disease (i.e. LGSC – previously known as “invasive implants”) is present, there IS an association with shorter disease-free and overall survival.
• We need data to determine the longterm outcome where SBOT is associated with small amounts of invasive peritoneal disease (i.e. LGSC), and compare this to the experiences of women diagnosed with typical OC who have peritoneal disease.

Lymph node involvement

• Lymph node involvement by SBOT is not considered metastatic disease: the benign nature of these lesions should be mentioned in the pathology report

Full paper online: Hauptmann, S., Friedrich, K., Redline, R. et al. Virchows Arch (2016). Ovarian borderline tumors in the 2014 WHO classification: evolving concepts and diagnostic criteria doi:10.1007/s00428-016-2040-8 [OPEN ACCESS]

Slides taken from: Smith (2014) What’s New in the 2014 WHO
Classification of Tumours of the
Female Genital Tract.  Presentation at Arab-Britsh School of Pathology, Cairo 2014