1. Review -Unusual orbital tumor-
R3정현진/Pf.양석우

2. Anatomy of orbits (connective tissue system)

4. Constrast enhancement pattern(present, absent, homogeneous, heterogeneous) DDx.
Enhancement의 특징은 fat suppressed postcontrast T1 weighted images
Non enhanced hemorrhagic processes, dens scar tissue, fluid collections, necrotic portions of a tumor
Gadolilnium enhanced MRI : assessing of fibrovascularization tissue proggression
Well circumscribed orbital tumors: cavernous hemangioma(homogenous enhance)
, neurilemmnoma, neurofibroma, fibrous histiocytoma, hemangiopericytoma

5. Orbital fibrous histiocytoma(1)
General consideration
- The most common mesenchymal orbital tumor in middle aged
- neoplasm composed of fibroblasts and histiocytes
- most : benign
some : locally aggressive or malignant
Clinical feature
Upper nasal quadrant mass, slow-growing, relatively firm masses.
Sx: proptosis, mass effect, decreased vision, double vision, pain, eyelid swelling, ptosis
Diphasic pattern with mainly storiform(matted) composed of fibrous spindle cells along with scattered area showing single or grouped foamy histiocytes
spindle-shaped, fibroblast-like cells, and more ovoid, sometimes lipidized histiocytic cells bundles of enlogated fibroblasts
Carwheel pattern of intertwining, elongated fibroblasts 주로 보임
Hematoxylin and eosin
Malignant : increased amount of lipid c cytoplasmic vacuoles of the tumor cells
Vimentin(+), S-100(-)

6. Orbital fibrous histiocytoma(2)
Diagnostic approachs
- MRI, CT: well-circumscribed, irregular mass of uniform density
- DDx: schwannoma, carvenous hemangioma
Pathology
- Several variant  diagnostic difficulty
- Immunohistry : DDx of spindle cell tumor
fibrous histiocytoma: CD34(-)
solitary fibrous tumor : CD34 strongly (+)
Tx- complete surgical resection d/t possible of recurrence, malignant formation
Swannoma: 조직 비슨 : spindle-shaped nuclei in a whirling or fascicular pattern with eosinophilic glassy cytoplasm
Gross: a lobulated, well circumscribed, firm, grayish white to yellow tna mass
Bx: cartwheel bundles of enlogated fibroblasts c spindle-shaped, uniformly staining nuclei set in a dense fibrous stroma
나누기 benign, intermediate, malignant
H&E, original magnification x 200
Figure 3 (above, left and right). Benign fibrous bistioc)toma of orbit displaying the characteristic storiform (cartwheel) pattern. Notice
the admixture of fibroblastic and histiocytic-like cells. The latter cells show plump vesicular nuclei. (Left, hematoxylin-eosin stain, x 115. AFIP
neg Right, hematoxylin-eosin stain, x305. AFIP neg )
Figure 4 (below, left). Benign fibrous histioc)'tonm of orbit with fascicles ofspindle-sbaped cells showing an ill-defined storiform pattern.
Focal collection of xantlionlatous cells are present. (ttematoxylin-eosin stain, x 195. AFIP neg )
Figure 5 (below, right). Some orbital fibrous histiocytonaas show fi)ci containing bland-appearing muhinucleated giant cells, probably of
histiocytic origin. (tlematoxylin-eosin stain, x260. AFIP neg )

7. Hemangiopericytoma(1)
A spectrum of pericyte proliferation
Histology
- a mixed pattern of ovoid cells and sinusoidal space formation, creating the classic ‘staghorn’ vascular pattern
Clinical features
- middle-aged adults as slowly progressing unilateral proptosis, often with pain and vision loss, frequent intracranial extension and invasion to sinus cavity

8. Hemangiopericytoma(2)
DDx
-MRI
T1: well defined hypointense mass
T2: less definition
-Meningioma, lymphangioma, carvenous hemangiona, schwannoma
Treatment
- En bloc excision with wide margins d/t high rate of malignant transformation and recurrence
- Adjunctive radiation therapy may be of benefits
조직” perivascular massing of pericytes
Silver-stained material reveals reticulin

9. Langerhans cell histocytosis(1)
General consideration
- Histopathologically chararacterized by proliferation of Langerhans cells
- Peak incidence at age 1 and 4
- Those with onset of disease earlier than 1 year of age have worst prognosis
-Severity can range from a benign unifocal bone lesion to aggressive multisystem disease
Clinical feature
-proptosis, redness, mass-like lesion
Langerhans cell: large cells with abundant ill-defined cytoplasm, contain typical oval or indented unclei, some of which are shaped like coffee beans with long, central, longitudinal grooves
Vimentin(+)HAM(+56)
Langerhans
CD1a S100(+): positive phenotype
CD45(+)
Histopathology of the same patients showing the presence of numeorus Langerhans cells suggesting Langerhans cell histiocytosis. A multinucleated giant cell is present (H and E, ×200). (d) The diagnosis of Langerhans cell histiocytosis was confimed with CD1a immunostaining (×200)

10. Langerhans cell histocytosis(2)
Diagnosis
-histopathology: presence of langerhans cells, characterized by distinct cell margin and pink granular cytoplasm
-CD1a immunstaining or the presence of birbeck granules in electron microscopy
Prognosis
The tumor cells are quite anaplastic
-> Langerhans cell sarcoma. The course of untreated disease is rapidly fatal. With intensive chemotherapy, 50% of patients survive 5 years. 17