Transcript Case Study - University of Pittsburgh

Case Study 54
Edward D. Plowey
Case History
 The patient is a 56 year old woman with recent onset
seizure-like spells.
 The patient has no significant past-medical history.
 The patient underwent an MRI study of the brain.
Question 1
Describe the findings in the following MRI images:
T2 FLAIR
T1
T1 + C
T1 + C
Answer
Two left middle cranial fossa lesions show small amounts of
vasogenic edema. T2 isointense to hypointense (larger, medial
lesion). The larger medial lesion shows T1 hyperintensity. Both of
these lesions demonstrate avid, homogenous contrast enhancement
and dural tails, consistent with meningiomas.
Question 2
Formulate a differential diagnosis for these lesions.
Answer
The differential diagnosis of this lesion includes:
Meningiomas
Hemangiopericytomas / Solitary fibrous tumor nodules
Melanocytomas
Metastatic tumors
Question 3: Intraoperative Consultation
 The patient was taken to the operating room for left frontal craniotomy and
resection of the tumors.
 The surgeons noted good resection planes and dark pigmentation in the extraaxial tumors. A gross photograph of the medial tumor is shown:
 An intraoperative consultation was performed on the lateral tumor. Identify the
pertinent findings in the virtual slide of the intraoperative smear preparation.
Diff-Quick Stained Touch Prep (Lateral Tumor)
Answer
 The intraoperative smear shows a cellular neoplasm with delicate
vasculature and extravasated erythrocytes. The epithelioid cells
show prominent tapered cytoplasmic stretching which contrasts
with the usual pulled-taffy effect in meningothelial cells. High
power views show frequent binucleate cells and occasional coarse
pigment-containing cells with eccentric nuclei (pigmented
macrophages). A few cells have prominent nucleoli, but mitotic
figures are difficult to find. Nucleoli and cytoplasmic granules are
better appreciated on the Diff-Quick stained touch prep.
 Question 4: What is your Intraoperative Diagnosis?
Answer
Intraoperative diagnosis:
A. Neoplastic.
B. Melanocytic neoplasm, defer to permanents for further
classification.
Question 5: Permanent Sections
Describe the relevant findings on the following virtual
permanent section slides of the two excised tumors:
Lateral tumor
Medial Tumor
Answer
 A section of the lateral tumor shows sheets of epithelioid cells with
granular cytoplasm and round nuclei with nucleoli. Mitotic figures
are difficult to identify and there is no significant cellular anaplasia
or necrosis. No brain invasion is seen. A few macrophages with
coarse pigment are seen in areas with small fresh hemorrhages.
The lateral tumor itself shows no significant pigment.
 In contrast, the medial tumor shows fascicles of spindled cells and
peripheral areas with prominent melanin pigment. The medial
tumor also shows a paucity of mitotic figures, no significant
anaplasia or necrosis and no brain invasion.
Question 5
What immunostains will you order to confirm your
diagnostic impressions?
Answer
 Useful immunostains include the following:
 Melanocyte differentiation markers, including
 Melan A (click to view virtual slides Tumor #1, #2)
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
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EMA
CD34
Pankeratin
Ki67 (click to view virtual slides Tumor #1, #2)
Question 6
What information do the special stains convey?
What is the final diagnosis?
Answer
 Melanocyte differentiation markers Melan A, HMB45 and S100 are
diffusely and strongly positive.
 Immunostains for EMA, CD34 and pankeratin are negative,
confirming that the tumors are not meningiomas, HPC/SFT or
metastatic carcinomas.
 Ki67 immunostains demonstrate very low proliferative indices in
both tumors.
 Final Diagnosis: MELANOCYTOMAS, WHO GRADE 1.
Discussion
Melanocytomas are benign tumors of meningeal melanocytes that are
treated with surgical excision. Elevated prevalence of mitotic figures
and brain invasion suggest the possibility of more aggressive clinical
behavior (recurrence). Progression of melanocytoma to malignant
melanoma is the subject of a rare case report (Roser et al., 2004).
Primary CNS malignant melanoma is diagnosed with the presence of
anaplasia, brisk mitotic activity, necrosis and brain invasion (Brat and
Perry, 2007). This diagnosis is made when metastasis from a primary
systemic melanoma is ruled out.
Melanocytomas most commonly involve regions with the highest
densities of leptomeningeal melanocytes, including the posterior fossa,
cervical spinal cord and bases of the temporal lobes.
Melanocytomas/melanocytosis of the middle cranial fossa may be
associated with an ipsilateral nevus of Ota.
References
 Brat DJ and Perry A. (2007). Melanocytic lesions. In WHO classification
of tumours of the central nervous system. Eds. Louis DN, Ohgaki H,
Wiestler OD and Cavenee WK. Lyon, France: International Agency for
Research on Cancer.
 Roser F, Nakamura M, Brandis A, Hans V, Vorkapic P, Samii M. (2004).
Transition from meningeal melanocytoma to primary cerebral melanoma.
Case report. J Neurosurg. 101:528-31.