Orbit Flashcards
7 bones of orbit
frontal, zygomatic, maxillary, lacrimal, ethmoid, sphenoid, palatine
volume of orbit
30cc
Most common congenital orbital cyst? Most common location?
dermoid cyst. superotemporal
3 most common pediatric orbital tumors?
dermoid cyst, capillary hemangioma, rhabdomyosarcoma
Early and late histology of NSOI/orbital pseudotumor/IOI
Early polymorphous infiltrate. Late fibrosis with interspersed lymphoid follicles. Affects any orbital tissue, including tendons (TED spares tendons). Perivenulitis can be a prominent feature
Most common cause of unilateral proptosis in adults? Bilateral?
TED. TED.
Histology of TED?
Inflammation of orbital connective tissue, inflammation and fibrosis of EOMs that spares tendons, adipogenesis
Most common muscles affected by TED?
Inferior and medial recti
What type of cell is upregulated 100-fold in TED?
orbital fibroblast (neural crest derivative)
Broad, nonseptated hyphae from orbital biopsy in patient with poorly-controlled DM?
mucormycosis (zygomycosis). Invade blood vessel walls and cause thrombosing vasculitis
Slowly progressive orbital inflammation, biopsy shows septated hyphae with 45 degree branching?
Sino-orbital Aspergillosis. Hard to treat, can be fatal if invades brain
Noninvasive fungal disease characterized by IgE hypersenitivity in atopic individuals?
Allergic fungal sinusitis
Most common primary orbital neoplasm in adults? 2nd MC?
lymphoma. 2nd: hemangioma
Most common orbital malignancy in children?
rhabdomyosarcoma
3 most common types of lacrimal gland tumors? Which is most common?
pleomorphic adenoma (benign mixed tumor), adenoid cystic carcinoma, adenocarcinoma
pleomorphic adenoma is most common
What immuno marker may be elevated in the sclerosing variant of IOI?
IgG4
granulomatous inflammation with vasculitis and necrosis?
Wegeners / microscopic polyangiitis with ganulomatosis
Biopsy of painless superotemporal orbital lesion reveals pseudoencapsulated mass with mixture of ductal-derived epithelial and stromal elements
pleomorphic adenoma of lacrimal gland. **Recur with incomplete excision, and recurrences can develop into adenoid cystic carcinoma
Biopsy in a 40 yo woman of a painful superotemporal orbital lesion reveals nonencapsulated mass with a Swiss-cheese pattern of ductal-like epithelial cells? Type of spread?
Adenoid cystic carcinoma. Pernieural spread
Red discoloration of child’s eyelid without fever or warmth?
Think Rhabdo!
Types of rhabdo? Most common? Best prognosis? Worst prognosis?
embryonal (most common), botryoid (best prognosis), alveolar (worst prognosis), pleomoprhic
Immunohistochemical markers for rhabdo?
desmin, muscle-sepcific actin, vimectin
Poorly cohesive rhabdomyoblasts separated by fibrous septae?
alveolar rhabdomyosarcoma
Workup for patient with suspected orbital lymphoma?
Biopsy of accessible lymph node preferred over orbital biopsy. *Include systemic workup: lymph node exam, CBC w/ dif, imaging of thorax and abdomen
Orbital biopsy reveals well differentiated lymphoid hyperplasia with germinal centers?
Reactive lymphoid hyperplasia
Orbital biopsy reveals diffuse lymphoid proliferation without germinal center?
Atypical lymphoid hyperplasia
Orbital biopsy reveals diffuse lymph nodal architecture with monoclonal expansion of CD20 cells?
B cell lymphoma
One half of malignancies arising in orbit and adnexa are___.
Non-Hodgkin lymphoma (includes B and T cell. B cell much more common)
Child presents with fluctuating unilateral proptosis. Biopsy reveals an unencapsulated mass of lymphatic vascular spaces and lymphoid aggregates in a fibrotic intersitium
lymphangioma
Most common spindle cell tumor of orbit? Most common orbital location? Immunohistochemistry stains?
fibrous hostiocytoma (fibroxanthoma). superonasal. CD45 and CD68
42 yo p/w painful proptosis and diplopia. Orbital biopsy shows staghorn vascular pattern with densely packed spindle cells that stain positive for CD34
hemangiopericytoma
Most common nerve sheath tumor in the orbit?
neurofibroma
Describe the 2 patterns of Schwannomas
Antoni A: densely packed spindle cells. Palisading of nuclei may for a Verocay body
Antoni B: loosely arranged mucoid stroma, represents degeneration within the tumor
Ground glass appearance with lytic foci and narrowing of optic canal on plain radiograph?
fibrous dysplasia
Most common orbital met in children? Women? Men?
neuroblastoma. breast. prostate
