MRCOG Part 2 – Gynaecological Problems SBAs

A 71 year old woman presents with a single episode of post-menopausal bleeding.She is very worried as her sister has recently died of endometrial cancer.  She is otherwise fit and well with a normal BMI and no significant past medical history.  Abdominal and speculum examination is unremarkable.  What is the next most appropriate investigation?

Which of the following is not a cause of an elevated CA-125 level?

A 27 year old presents with a painful left vulval swelling for the past two days.  On examination, there is an erythematous fluctuant vulval lump at the left introitus, measuring approximately 3cm in diameter.  Her observations are as follows: RR 14, Sats 99% on room air, P 82, BP 128/87, Temp 36.5.  What is the next appropriate management?

A 27 year old presents with a painful left vulval swelling for the past two days.On examination, there is an erythematous fluctuant vulval lump at the left introitus, measuring approximately 3cm in diameter.  Her observations are as follows: RR 24, Sats 99% on room air, P 129, BP 98/54, Temp 39.9.  What is the next appropriate management?

A 27 year old presents with a painful left vulval swelling for the past two days. On examination, there is an erythematous fluctuant vulval lump at the left introitus, measuring approximately 3cm in diameter.  Her GP refers her as an emergency to gynaecology and she has an incision and drainage with marsupialisation.  She represents on three occasions subsequently with recurrence of her symptoms.  What is the next appropriate management?

Which of the following is not a potential symptom of endometriosis?

Which of the following statements regarding endometriosis is incorrect?

A 17 year old presents with a three year history of debilitating cyclical pelvic pain. She reports severe dysmenorrhoea with heavy menstrual bleeding such that she is often absent from school for four days during her periods.  Her past medical history includes severe asthma with a history of hospital admission as a young child. She is not yet sexually active. What is the most appropriate management?

A 60 year old woman presents with severe vulval itching and soreness. On examination, there are pale white atrophic areas of the vulva and fusion of the labia minora in the midline but no involvement of the vaginal mucosa.  What is the likely diagnosis?

A 60 year old woman presents with severe vulval itching and soreness. On examination, there are pale white atrophic areas of the vulva and fusion of the labia minora in the midline but no involvement of the vaginal mucosa.  What is the most appropriate management?

A 48 year old woman presents with increasingly heavy periods for the past six months, despite taking regular tranexamic acid. She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  What is the next most appropriate investigation?

A 71 year old woman presents with a single episode of post-menopausal bleeding.She is very worried as her sister has recently died of endometrial cancer.  She is otherwise fit and well with a normal BMI and no significant past medical history.  Abdominal examination is unremarkable and speculum examination reveals atrophic vaginal mucosa but no other obvious abnormality.  A transvaginal pelvic ultrasound scan shows a normal size anterverted uterus with endometrial thickness of 2mm and no other abnormality seen.  What is the next most appropriate management?

A 38 year old woman presents with increasingly heavy periods for the past six months.She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  What is the next most appropriate investigation?

A 48 year old woman presents with increasingly heavy periods for the past six months.  She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  On examination, she is found to have a palpable fibroid uterus, approximately 20 week size.  What is the next most appropriate management?

A 48 year old woman presents with increasingly heavy periods for the past six months.  She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  Which of the following is not a cause of heavy menstrual bleeding?

A 21 year old woman presents as she is concerned that her periods are abnormally long.  She reports that she bleeds for 12-14 days and that her cycle occurs every 35 days.  What is the normal average duration of menstruation?

A 21 year old woman presents as she is concerned that her periods are irregular.  She reports that she has periods every 37 days and that her cycle can vary by up 10 days.  What is the normal cycle frequency of menstruation?

A 38 year old woman presents with increasingly heavy periods for the past six months.  She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  Physical examination is normal and a full blood count shows a normal haemoglobin.  What is the most appropriate management?

A 38 year old woman presents with increasingly heavy periods for the past six months.  She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  Physical examination is normal and a full blood count shows a normal haemoglobin. After discussion of treatment options with her, she is reluctant to use hormonal treatment.  What is the most appropriate management?

A 38 year old woman presents with increasingly heavy periods for the past six months.  She reports that her menstrual cycles are approximately 30 days in length with prolonged heavy bleeding for 10-14 days where she has to use dual protection of tampons and sanitary towels.  Physical examination is normal and a full blood count shows a normal haemoglobin. After discussion of treatment options with her, she expresses a wish to have a treatment that is also an effective contraceptive but she has had a poor experience with a coil in the past.  What is the most appropriate management?

A 38 year old woman presents with increasingly heavy periods for the past six months and after discussion, opts to have a Mirena LNG-IUS inserted. Which of the following is a common unwanted outcome of the LNG-IUS?

A 38 year old woman presents with increasingly heavy periods for the past six months and after discussion, opts to have injectable long-acting progestogens.Which of the following is an uncommon unwanted outcome of injectable long-acting progestogens?

A 71 year old woman presents with a single episode of post-menopausal bleeding.She is very worried as her sister has recently died of endometrial cancer.  She is otherwise fit and well with a normal BMI and no significant past medical history.  Abdominal examination is unremarkable and speculum examination reveals atrophic vaginal mucosa but no other obvious abnormality.  Her GP arranges a transvaginal pelvic ultrasound scan which shows a normal size anteverted uterus with homogenous endometrium with thickness of 8mm and no other abnormality seen.  What is the next most appropriate management?

A 38 year old woman presents with increasingly heavy periods for the past six months and after discussion, opts to have oral progestogens.  Which of the following is a rare unwanted outcome of oral progestogens?

A 43 year old woman presents feeling generally tired and lethargic. She is Para 2 having had two vaginal deliveries and her family is complete. A full blood count shows that she is anaemic with a haemoglobin of 84g/L and on further questioning, she reports that she has always had very heavy periods and is known to have fibroids.  An ultrasound scan which shows multiple fibroids, of which the largest is 5cm.  She opts to have uterine artery embolization as she would prefer to avoid surgical treatment but at follow up of 6 months, she has not experienced significant improvement in her symptoms. What is the most appropriate management?

­A 38 year old woman presents with increasingly heavy periods for the past six months and after discussion, opts to have tranexamic acid.Which of the following statements regarding the use of tranexamic acid is incorrect?

A 43 year old woman presents with increasingly heavy periods.She has tried tranexamic acid without any obvious benefit and she is requesting to have her Mirena removed due to persistent spotting.  Her family is complete and she is extremely fed up with her symptoms and asks for definitive treatment.  What is the most appropriate treatment?

A 43 year old woman presents with increasingly heavy painful periods.  She is known to have large fibroids and reports significant pressure symptoms of urinary frequency.  Her GP refers her to secondary care and after discussion of all treatment options with the gynaecologist, she opts to have a hysterectomy.  What is the most appropriate treatment?

A 43 year old woman presents with increasingly heavy painful periods.  She is known to have large fibroids and reports significant pressure symptoms of urinary frequency.  Her GP refers her to secondary care and after discussion of all treatment options with the gynaecologist, she opts to have a hysterectomy.  Which of the following statements is incorrect regarding removal of ovaries at hysterectomy?

A 23 year old presents with secondary amenorrhoea for 6 months.  She is nulliparous with a BMI of 36 and her periods have always been irregular with 55-60 day cycles on average. She also reports significant hirsutism and acne.  What is the next most appropriate investigation?

A 23 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 36 and her periods have always been irregular with 55-60 day cycles on average.  Several pregnancy tests have all been negative. Transvaginal ultrasound shows evidence of polycystic ovaries.  Further investigations including hormone profile, testosterone, thyroid function and prolactin are normal.  Her GP makes a diagnosis of polycystic ovarian syndrome (PCOS).  Which of the following is not associated an increased risk in patients with PCOS?

A 23 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 36 and her periods have always been irregular with 55-60 day cycles on average.  Several pregnancy tests have all been negative. Transvaginal ultrasound shows evidence of polycystic ovaries and a thickened cystic endometrium measuring 36mm.  Further investigations including hormone profile, testosterone, thyroid function and prolactin are normal.  What is the most appropriate management?

A 23 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 36 and her periods have always been irregular with 55-60 day cycles on average. A urinary pregnancy test is negative but she reports alopecia, worsening acne and recently a deepening of her voice.  Her blood results are shown below with normal ranges shown in brackets:

FSH – 10.5                   (1.0-11.0 IU/L)

LH – 8.5                       (0.5-14.5 IU/L)

Testosterone – 7.8      (0.8-3.1 nmol/L)

Prolactin – 401            (90-520 mu/L)

TSH – 2.1                     (0.5-7.0 mu/L)

Free T4 – 20                (11-23 pmol/L)

What is the next most appropriate investigation?

A 71 year old woman is being investigated for a recent change in bowel habit and undergoes a CT Colon with contrast. The CT is reported as showing no obvious bowel pathology but comments that there is 8mm homogenous endometrium.  The patient reports that she has not had any post-menopausal bleeding and is otherwise asymptomatic.  What is the next appropriate management?

A 28 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 24 and her periods have always been regular previously. A urinary pregnancy test is negative but she reports that she has been experiencing some hot flushes in the last few months.  Her blood results are shown below:

FSH – 45                      (1.0-11.0 IU/L)

LH – 30                        (0.5-14.5 IU/L)

Oestradiol – 80           (70-510 pmol/L)

Testosterone – 1.8      (0.8-3.1 nmol/L)

Prolactin – 401            (90-520 mu/L)

TSH – 2.1                     (0.5-7.0 mu/L)

Free T4 – 20                (11-23 pmol/L)

What is the next most appropriate investigation?

A 23 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 31 and her periods have always been irregular with 55-60 day cycles on average. A urinary pregnancy test is negative but she reports that she has been experiencing significant headaches for the last few months and has noticed galactorrhoea.  Her blood test results are shown below:

FSH – 10.5                   (1.0-11.0 IU/L)

LH – 8.5                       (0.5-14.5 IU/L)

Testosterone – 1.8      (0.8-3.1 nmol/L)

Prolactin – 3069          (90-520 mu/L)

TSH – 2.1                     (0.5-7.0 mu/L)

Free T4 – 20                (11-23 pmol/L)

What is the next most appropriate investigation?

A 23 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 31 and her periods have been irregular for the last three years with cycles varying between 2 and 4 months apart. A urinary pregnancy test is negative.  Her past medical history includes irritable bowel syndrome for which she takes regular antispamodics and metoclopramide.  Her blood test results are shown below:

FSH – 10.5                   (1.0-11.0 IU/L)

LH – 8.5                       (0.5-14.5 IU/L)

Testosterone – 1.8      (0.8-3.1 nmol/L)

Prolactin – 996            (90-520 mu/L)

TSH – 2.1                     (0.5-7.0 mu/L)

Free T4 – 20                (11-23 pmol/L)

What is the next most appropriate investigation?

A 19 year old presents with secondary amenorrhoea for 6 months.She is nulliparous with a BMI of 15.1 and her periods started at the age of 12 years old and were previously regular.  She is currently in her first year at university studying medicine and is not sexually active.  She reports that she has become very health conscious in the past year, eating a vegan diet and has lost 10kg of weight.  Her blood test results are shown below:

FSH – 1.1                     (1.0-11.0 IU/L)

LH – 0.6                       (0.5-14.5 IU/L)

Oestradiol – 49           (70-600 pmol/L)

Testosterone – 1.3      (0.8-3.1 nmol/L)

Prolactin – 600            (90-520 mu/L)

TSH – 1.5                     (0.5-7.0 mu/L)

Free T4 – 20                (11-23 pmol/L)

What is the likely diagnosis?

A 33 year old woman presents with cyclical mood swings.  She is nulliparous and has regular periods every 30 days which are heavy and painful.  She reports that she feels extremely tense and anxious during two weeks prior to her periods, to the extent that she has been uncharacteristically aggressive towards her partner and has had to take time off from work.  She also experiences headaches, bloating and breast tenderness.  She is very worried that she has a mental health disorder as her mother suffered from bipolar disorder.  She has no significant past medical history and physical examination is normal, except for her BMI of 36.  What is the next most appropriate management?

A 33 year old woman presents with cyclical mood swings.  She is nulliparous and has regular periods every 30 days which are heavy and painful.  She reports that she feels extremely tense and anxious during two weeks prior to her periods, to the extent that she has been uncharacteristically aggressive towards her partner and has had to take time off from work.  She also experiences headaches, bloating and breast tenderness.  Her GP asks her to keep a symptom diary for three months and her symptoms are confirmed as starting mid-cycle and resolving within a day of menstruation.  What is the next most appropriate management?

A 33 year old woman presents with cyclical mood swings where she feels extremely tense and anxious during two weeks prior to her periods, to the extent that she has been uncharacteristically aggressive towards her partner and has had to take time off from work.  Her GP suspects severe premenstrual syndrome and refers her to secondary care after commencing initial treatment in primary care with no success.  The gynaecologist commences her on GnRH analogues with add-back HRT.   Which of the following statements about this treatment is incorrect?

A 40 year old woman presents with increasing abdominal swelling. She has previously had an open myomectomy for uterine fibroids and is concerned that they have recurred.  On examination, she is found to have a bulky enlarged uterus with palpable fibroids, approximately equivalent to a 28 week size pregnancy.  Which of the following is not a typical presentation of uterine fibroids?

A 26 year old woman presents with a three month history of persistent post-coital bleeding.  She has noticed a small amount of fresh bright red blood following intercourse lasting approximately 1-2 days but denies abdominal pain or dyspareunia.  She is nulliparous and her periods are regular with a 28 day cycle.  She has been taking the combined oral contraceptive pill for the last four months since starting a new relationship.  She has had two other sexual partners and has not yet had a cervical smear.  Abdominal examination is unremarkable and speculum examination reveals a symmetrical florid red area around the external cervical os that bleeds on contact.  Which of the following tests is not indicated?

A 26 year old woman presents with a three month history of persistent post-coital bleeding.  She has noticed a small amount of fresh bright red blood following intercourse lasting approximately 1-2 days but denies abdominal pain or dyspareunia.  She is nulliparous and her periods are regular with a 28 day cycle.  She has been taking the combined oral contraceptive pill for the last four months since starting a new relationship.  She has had two other sexual partners and has not yet had a cervical smear.  Abdominal examination is unremarkable and speculum examination reveals a symmetrical florid red area around the external cervical os which bleeds on contact.  Which of the following is the most likely diagnosis?

A 71 year old woman is being investigated for a recent change in bowel habit and undergoes a CT Colon with contrast.  The CT is reported as showing no obvious bowel pathology but comments that there is evidence of a thickened endometrium.  The patient reports that she has not had any post-menopausal bleeding and is otherwise asymptomatic.  A transvaginal pelvic ultrasound scan shows an anteverted uterus with cystic appearance of the endometrium measuring 12mm in thickness.  What is the next most appropriate management?

A 26 year old woman presents with a three month history of persistent post-coital bleeding.She has noticed a small amount of fresh bright red blood following intercourse lasting approximately 1-2 days but denies abdominal pain or dyspareunia.  She is nulliparous and her periods are regular with a 28 day cycle.  She has been taking the combined oral contraceptive pill for the last four months since starting a new relationship.  She has had two other sexual partners and has not yet had a cervical smear.  Abdominal examination is unremarkable and speculum examination reveals a symmetrical florid red area around the external cervical os that bleeds on contact.  An STI screen with triple swabs and a cervical smear is performed and both of which are subsequently reported as negative.  Which of the following is the most appropriate management?

A 29 year old woman presents with intermenstrual and post-coital bleeding.  She has noticed a small amount of fresh bright red blood immediately following intercourse but also reports erratic fresh bleeding mid-cycle.  She denies abdominal pain or dyspareunia and her periods are regular with a 30 day cycle.  She has been taking the combined oral contraceptive pill for several years and has been in a stable relationship with the same partner for the past nine years.  She is up to date with her routine cervical smear, which was normal one year previously.  Abdominal examination is unremarkable and speculum examination reveals a small 7mm mobile pink smooth mass protruding through the external cervical os.  What is the most appropriate management?

A 47 year old woman presents to her GP with intermenstrual and post-coital bleeding.  She has noticed a small amount of fresh bright red blood immediately following intercourse but also reports erratic fresh bleeding mid-cycle.  She denies abdominal pain or dyspareunia and her periods are regular with a 30 day cycle.  She has been taking the progesterone only contraceptive pill for several years and has been in a stable relationship with the same partner for the past twenty years.  She is up to date with her routine cervical smear which was normal one year previously.  Abdominal examination is unremarkable and speculum examination reveals a small 7mm mobile pink smooth mass protruding through the external cervical os.  What is the most appropriate management?

Which of the following is not a contraindication to endometrial ablation?

A 71 year old woman presents with a single episode of post-menopausal bleeding.She is very worried as her sister has recently died of endometrial cancer.  She is otherwise fit and well with a normal BMI and no significant past medical history.  Abdominal and speculum examination is unremarkable.  A transvaginal pelvic ultrasound scan shows a normal size anterverted uterus with a 12mm endometrial polyp arising at the fundus of the uterus with endometrial thickness of 3mm.  What is the next most appropriate management?

A 65 year old woman is investigated for severe lower back pain and is referred for an MRI Spine. The MRI is reported as follows:

“Moderate osteoporotic changes of the lumbar spine.  A left ovarian cyst is seen which appears simple in nature and measures 6cm in diameter.  Gynaecological referral is advised.”

What is the most appropriate investigation?

A 24 year old woman presents with persistent lower abdominal pain which is relieved by opening her bowels. A transvaginal ultrasound scan is reported as follows:

Normal appearance of anteverted uterus with regular endometrium measuring 4mm.  Simple anechoic left ovarian cyst measuring 25 x 21 x 28 mm in diameter.  Normal right ovary.  No free fluid.

What is the next appropriate management?

A 24 year old woman presents with persistent lower abdominal pain which is relieved by opening her bowels.A transvaginal ultrasound scan is reported as follows:

Normal appearance of anteverted uterus with regular endometrium measuring 4mm.  Complex septated left ovarian cyst measuring 75 x 51 x 68 mm in diameter.  Normal right ovary.  No free fluid.

What is the next appropriate management?

A 34-year-old woman presents to the gynaecology assessment unit with a 6-hour history of sudden onset, severe right lower abdominal pain and vomiting. She is haemodynamically stable and apyrexial. She has had two previous vaginal deliveries and urinary pregnancy test is negative. Transvaginal ultrasound shows a mildly enlarged right ovary with peripheral follicles, no dominant cyst, and reduced venous flow on Doppler.  She undergoes diagnostic laparoscopy and is found to have a right ovarian torsion. Which of the following is most strongly associated with an increased risk of ovarian torsion?

A 24-year-old woman presents with sudden-onset severe right lower abdominal pain and vomiting. She has no known medical conditions and is not pregnant. Transvaginal ultrasound shows an enlarged, normal-appearing right ovary with peripheral follicles and reduced venous flow. Laparoscopy confirms ovarian torsion. The ovary is detorsed and found to be normal, with no cyst or mass. No further surgical intervention is performed. She is now recovering and asks about the chances of this happening again in the future. What is the approximate risk of recurrence of ovarian torsion in this scenario?

A 28-year-old woman presents to A&E with sudden-onset severe lower abdominal pain and vomiting. She is apyrexial and haemodynamically stable. She has no significant past medical history and is not pregnant. Ultrasound shows a 7 cm right ovarian mass with mixed echogenicity, peripheral follicles, and reduced venous flow. CA125 is mildly elevated at 45. She undergoes emergency laparoscopy, and the ovary is detorsed and preserved. She is concerned about the possibility of ovarian cancer and asks about the risk of malignancy associated with torsion. What is the approximate risk of malignancy in ovarian torsion in premenopausal women?

A 67-year-old postmenopausal woman presents with sudden-onset left iliac fossa pain and vomiting for the past 6 hours. She is haemodynamically stable and afebrile. Transvaginal ultrasound shows an 8 cm complex left adnexal mass with solid and cystic components, no papillary projections, and absent Doppler flow. There is no ascites. Her serum CA125 is elevated at 940 U/mL. She is scheduled for urgent diagnostic laparoscopy due to suspected ovarian torsion. During the pre-operative counselling, she asks whether this could be ovarian cancer. What is the approximate risk of malignancy in postmenopausal women presenting with ovarian torsion?

A 30-year-old woman presents to the emergency department with a 6-hour history of sudden-onset severe right iliac fossa pain and nausea. She has regular menstrual cycles and is not currently using any contraception. Urine pregnancy test is negative. A transvaginal ultrasound shows an enlarged right ovary measuring 7 cm, with peripheral follicles and oedematous stroma. Free fluid is noted in the Pouch of Douglas. Colour Doppler flow is inconclusive. The sonographer also notes a twisted vascular pedicle adjacent to the ovarian hilum. Which of the following ultrasound features has the highest positive predictive value for ovarian torsion?

A 24-year-old woman presents with sudden-onset severe right lower abdominal pain and vomiting. She has no known medical conditions and is not pregnant. Transvaginal ultrasound shows an enlarged, right ovary containing a 5cm dermoid cyst reduced venous flow. Laparoscopy confirms ovarian torsion. The ovary is detorsed and the operating surgeon decides to complete the operation following detorsion and arrange an interval ovarian cystectomy instead as the affected ovary is noted to be oedematous. What is the approximate risk of recurrence of ovarian torsion whilst awaiting interval cystectomy in this scenario?

A 34-year-old woman attends the vulval clinic with a 6-month history of a persistent vulval lesion associated with mild pruritus. She is a smoker and has a history of cervical high-risk HPV infection. On examination, there is a well-defined, slightly raised hyperpigmented plaque on the right labia minora. There is no ulceration or induration. A vulval biopsy is performed. The histology shows basal layer atypia with high nuclear-to-cytoplasmic ratios, hyperchromasia, pleomorphism, cytological atypia and mitoses without stromal invasion. What is the likely diagnosis?

A 34-year-old woman attends the vulval clinic with a 6-month history of a persistent vulval lesion associated with mild pruritus. She is a smoker and has a history of cervical high-risk HPV infection. On examination, there is a well-defined, slightly raised hyperpigmented plaque on the right labia minora. There is no ulceration or induration. A vulval biopsy is performed. The histology shows basal layer atypia with high nuclear-to-cytoplasmic ratios, hyperchromasia, pleomorphism, cytological atypia and mitoses with stromal invasion.  What is the likely diagnosis?

A 68-year-old postmenopausal woman presents with long-standing vulval itching and soreness. She has a background of biopsy-proven vulval lichen sclerosus treated intermittently with topical corticosteroids. Examination reveals a poorly defined, thickened pale area with focal erythema on the labia majora. A punch biopsy is performed due to concern about malignant transformation. The histology shows basal layer atypia with acanthosis, occasional parakeratosis, and irregular elongation and anastomoses of the rete ridges without stromal invasion. What is the likely diagnosis?

A 68-year-old postmenopausal woman presents with long-standing vulval itching and soreness. She has a background of biopsy-proven vulval lichen sclerosus treated intermittently with topical corticosteroids. Examination reveals a poorly defined, thickened pale area with focal erythema on the labia majora. A punch biopsy is performed due to concern about malignant transformation. The histology shows basal layer atypia with acanthosis, occasional parakeratosis, and irregular elongation and anastomoses of the rete ridges with stromal invasion. What is the likely diagnosis?

A 34-year-old woman attends the vulval clinic with a 6-month history of a persistent vulval lesion associated with mild pruritus. She is a smoker and has a history of cervical high-risk HPV infection. On examination, there is a well-defined, slightly raised hyperpigmented plaque on the right labia minora. There is no ulceration or induration. A vulval biopsy is performed. The histology shows basal layer atypia with high nuclear-to-cytoplasmic ratios, hyperchromasia, pleomorphism, cytological atypia and mitoses without stromal invasion.  A diagnosis of high grade squamous intra-epithelial neoplasia is made.  What is the risk of malignant transformation to squamous cell carcinoma?

A 68-year-old postmenopausal woman presents with long-standing vulval itching and soreness. She has a background of biopsy-proven vulval lichen sclerosus treated intermittently with topical corticosteroids. Examination reveals a poorly defined, thickened pale area with focal erythema on the labia majora. A punch biopsy is performed due to concern about malignant transformation. The histology shows basal layer atypia with acanthosis, occasional parakeratosis, and irregular elongation and anastomoses of the rete ridges without stromal invasion. A diagnosis of differentiated vulvar intra-epithelial neoplasia is made.  What is the risk of malignant transformation to squamous cell carcinoma?