Case Presentation
A 20-year-old lady presented with complaints of abdominal pain for 6
months, which was of mild intensity at first but gradually increased in
intensity over the last few days before the presentation. It was present
in the lower abdomen initially however progressed to generalized
abdominal pain with an increase in intensity. She did not have any
urinary complaints, fever, nausea or vomiting. She presented on the
3rd day of her menstrual cycle, which was of normal
duration and flow in regular intervals of 28+/- 2 days. She did not give
any significant medical or surgical history in the past. No significant
history was found in the family either.
On examinations, she was a healthy-looking female, with no pallor, or
lymphadenopathies. She had a soft, scaphoid abdomen, with a vague mass
palpable in the left iliac fossa, ~6x6cm in diameter,
with ill-defined margins, non-tender, and not attached to the overlying
skin. Bowel sounds were present on auscultation. Other systemic
examinations were normal.
On ultrasonography, a complex heterogenous solid-cystic lesion was seen
in the left adnexa measuring ~9.9 x 6.0x 6.4 cm. MRI was
then done to confirm the diagnosis, which showed an 11.7 x 8.2x4.8cm
(CCxAPxT) size complex heterogenous signal intensity mass in the
retroperitoneum just medial to the left psoas muscle and lateral to
iliac vessels. (Figure 1) Anteriorly the mass was extending up to the
anterior abdominal wall, displacing the psoas muscle laterally and iliac
vessels medially. Multiple variable size irregular shape cystic areas
were seen within it. Variable thickness septa and solid components were
present. Multiple flow void areas were noted in the mass, suggesting
marked vascularity. Which gave a differential diagnosis of
retroperitoneal soft tissue sarcoma or neurogenic tumour.
So, with the provisional diagnosis of Primary Retroperitoneal Mass, the
patient underwent “Laparoscopy Assisted Transperitoneal Excision of
Retroperitoneal Mass”. During surgery, a large mass measuring
~15x10cm solid mass with 2 lobes with an irregular
surface was seen with the larger lobe having cystic areas. (Figure 2)
There was dense adhesion of the mass posteriorly with the psoas muscle.
The visualized retroperitoneal organs were normal. There was blood loss
of ~1000ml from the part of the mass adhered to the
psoas muscle. An intra-abdominal drain was placed, which was removed on
the 4th postoperative day. The rest of her stay in the
hospital was uneventful and was sent home from the hospital on the
6th postoperative day.
In her histopathology report, gross examination showed 2 large nodular
bosselated encapsulated soft tissue measuring 9x6x2cm and 4.5x3x3cm were
seen with a cut section showing a grey-white area with a cystic area
within it. (Figure 3 (A) and (B)) On microscopic examination, mitotic
figures or necrosis were not present, Tumour was composed of compact
cellular and loose myxoid areas with spindle-like cells and ovoid cells
coursed by round to slit-like and occasionally ramifying capillary
seized vessels, (Figure 4 (A)) punctuated by variously sized
hemangiopericytomatous vessels, many with discernible fibromuscular
walls and cystic spaces. The morphological features which were
consistent with Solitary Fibrous Tumour and margins, however, were
positive for tumour.
The Immunohistochemistry showed Tumour cells positive for CD34, SMA and
STAT-6 and negative for CK, S100 and desmin. (Figure 4 (B) and (C)) The
Ki67 proliferation index was 10%.
The risk of metastasis according to Demicco et al: overall risk class:
low (2/7).
Age <50 years (Score 0); Tumour size 10-15cm (Score:2);
Mitotic count 0/10HPF (Score 0); Tumour Necrosis <10% (Score
0)
The patient was followed up at 3 months and 6 months with
Contrast-enhanced computed tomography, which did not show any
recurrences.