Results :
We present here the clinicopathologic details of the 3 cases (see Table
1 for summary). Biallelic mutations in the DICER1 gene on exon
11, was detected in all 3 tumors. Germline testing was possible only in
1 case.
Clinical features
Case 1
A 12-year-old female presented with headache, vomiting, left hemiparesis
and an episode of generalized seizure. Magnetic resonance imaging (MRI)
brain (Figure 1a) showed a heterogeneous lesion with postcontrast
enhancement in the right fronto-parietal para-falcine region with
surrounding edema and midline shift. Imaging revealed no additional
findings. History of an aunt who died of recurrent gynecologic
malignancy at 39 years was noted. After gross total resection, radiation
therapy (59.4Gy in 33 fractions) was administered. Follow-up chest
computed tomography (CT) scans showed multiple, small pulmonary nodules
(<4mm). Adjuvant chemotherapy with vincristine, doxorubicin
and cyclophosphamide (VDC) alternating with cisplatin, etoposide and
ifosfamide (PEI) was administered for 10 weeks, followed by vincristine,
dactinomycin and cyclophosphamide (VAC) upto 45 weeks. Magnetic
resonance imaging (MRI) brain revealed no tumour and positron emission
tomography (PET) scan showed few calcified FDG non-avid nodules at the
end of therapy. The child’s current surveillance protocol includes 6
monthly CT chest and ultrasound (USG) pelvis and 2 yearly USG thyroid.
She remains in remission after 3 years.
Case 2
A 16-year-old girl presented with abdominal pain and decreased appetite.
An emergency laparotomy revealed a necrotic mass based in the broad
ligament, involving both adnexae, pouch of Douglas with extensive
omental and peritoneal deposits (Fig. 1b). Residual tumour responded
well to adjuvant chemotherapy with VDC alternating with PEI (6 cycles)
(Fig. 1c). Following chemotherapy, a debulking procedure included left
salpingo-oophorectomy, total omentectomy and excision of peritoneal
deposits. The patient is on maintenance chemotherapy with vinorelbine
and cyclophosphamide and is doing well 6 months post-surgery. No
significant family history was noted.
Case 3
A five-month-old female presented with a mass protruding into vaginal
introitus. Imaging revealed no other lesion. The initial biopsy was
reported as an embryonal rhabdomyosarcoma.
The patient was treated with chemotherapy as per the RMS 2005 EpSSG
protocol including ifosfamide, vincristine and dactinomycin. Interim
assessment after 4 months suggested suboptimal response. She received
second line chemotherapy including doxorubicin and carboplatin for 6
months. Reassessment MRI showed a small vaginal nodule with fibrotic
signal (Fig. 1d). The parents refused local treatment with radiotherapy
and she was followed with imaging-based surveillance. After 6 months a 2
cm mass extruding into vagina was seen. Repeat scans showed a large
recurrent tumour (Fig. 1e, f) with retroperitoneal lymph nodes and mural
nodules in the colon. Chemotherapy was commenced with vincristine,
irinotecan and temozolomide, however further progression prompted
initiation of salvage chemotherapy with PEI alternating with VDC.
Despite good response, the parents refused further surgery or
radiotherapy. Family history was not contributory, and the family did
not consent to germline testing. She had massive progression of disease
and was lost to follow-up 2.5 years from presentation.
Pathologic findings :
Case 1
Both resections showed sheets of small round to spindled primitive
blastemal cells, with condensed chromatin and small nucleoli. Nodules of
immature cartilage were seen to arise abruptly, in the midst of
blastemal cells (Fig. 2a-f). Some foci showed alternating hyper and
hypocellular spindle cells foci with larger vesicular nuclei and
prominent nucleoli (Fig. 2d). Brisk mitoses and apoptosis is noted in
both blastemal and sarcomatous foci.
Immunohistochemistry (IHC) with desmin, myogenin, myoD1 and CD99 showed
patchy but strong staining in the spindle cell component, while GFAP,
smooth muscle actin, synaptophysin and NSE were negative. INI1 was
retained in the tumour cells. S100 stained the chondroid elements but
was negative in the spindle cell component. Ki 67 proliferation index
was >90%.
Case 2
Grossly, the tumour was a single solid-cystic mass measuring 10.0 x 5.5
cm, with multiple irregular, friable projections. On microscopy,
alternating sheets and ribbons/trabeculae of densely packed primitive
blastemal, monotonous small, round to spindle shaped cells, were
separated by hypocellular areas of small spindle cells in collagenized
to loose, myxoid stroma (Fig. 3a-f). Areas of perivascular tumour cells,
condensation, microcystic foci and cambium-like concentration below
pseudocystic spaces were noted (Fig. 3b, 3c). Sarcomatous overgrowth of
large spindle cells with abundant clear to eosinophilic cytoplasm,
coarse chromatin and prominent nucleoli was present (Fig 3e-f). Brisk
mitoses (18-20 per 10 high power fields) including atypical forms and
necrosis were identified. Focal immature cartilage was identified in 1
slide (Fig. 3a). The tumour showed a prominent vascular pattern with
large dilated blood vessels with thin wall.
Immunohistochemically tumour cells were diffusely positive for desmin
and myogenin. There was patchy positivity for myoD1, while AFP, SALL4,
CD30, CK, inhibin, PAX8 and WT-1 were negative. INI1 was retained.
Cytogenetic studies for PAX-3 or FOXO1 rearrangements were negative.
Case 3
The initial biopsy of the tumour showed multiple tumour fragments lined
by squamous epithelium (Fig. 4a-f). A largely hypocellular pattern with
small, bland spindle or stellate cells resided in a myxoid background
with an immature mesenchymal appearance with focal hypercellular areas
and perivascular condensation by smaller, angulated cells. These cells
also showed subepithelial concentration, forming a cambium-like layer
(Fig. 4b). Also noted were larger blastemal cells with coarse nuclear
chromatin and prominent nucleoli, arranged in nests, cords and rosette
formations, with a granular pink neuropil-like background (Fig. 4e).
Sarcomatous areas composed of nests of larger cells with vesicular
nuclei, prominent nucleoli and moderate clear cytoplasm, were also noted
(Fig. 4f). Mitotic figures were brisk and more frequent in these foci,
along with prominent apoptosis. Cartilage was not identified.
On IHC, myoid markers – desmin (Fig. 4b; inset), myogenin, and myoD1
showed patchy positivity in the small, spindle shaped cells, while the
larger blastic cells in cords, nests and rosettes were non-reactive.
Both components of the tumour are negative for cytokeratin (AE1/AE3),
inhibin, SALL4, synaptophysin and CD99.
The second biopsy of the small residual nodule, showed hypocellular
tissue with scattered, bland, spindled to stellate cells, in a loose
collagenous background. Few of the spindle cells were desmin positive.
No blastemal cells were identified in this biopsy. (Fig. 4g)
The third biopsy of the recurrent tumour, revealed sarcomatous
overgrowth, comprising of sheets and nests of round to spindle shaped
large cells, with coarse chromatin and abundant mitoses and apoptosis.
These cells were morphologically similar to the large blastic cells in
cords and nests in the initial biopsy but showed greater degree of
anaplasia. (Fig. 4h, i) On IHC, the cells showed no rhabdomyoblastic
differentiation, being negative for desmin, myoD1 and myogenin. The
tumour cells were diffusely positive for CD99 and SALL4 (Figure 3i;
inset), focally positive for synaptophysin and neuron specific enolase
(NSE). The tumour cells were negative for chromogranin, cytokeratin
(AE1/AE3), calretinin, inhibin, S100, Oct3/4, CD45 and Tdt. INI1 was
retained. FISH for EWSR1 gene rearrangement was negative.