Ocular Pathology

Use it to review eye pathology for Ophthalmology Board Review or OKAP. Anatomy and pathology of the human eye. Included solar-lentigo, phakomatous choristoma (phacomatous-choristoma), congenital hereditary endothelial dystrophy, Fuch's dystrophy, bullous keratopathy, conjunctival nevus, syringoma, primary acquired melanosis,carcinoma-in-situ, BIGH3 dystrophy, and other lesions seen in eye-pathology. The cornea, iris, lens, sclera, retina and optic nerve are all seen.

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Sunday, January 28, 2007

Osteoma of the Choroid (Osseous Choristoma)


Choroidal Osteoma
Definition: Benign choroidal tumor composed of mature bone that was described in 1978.
Incidence/ Prevalence: The tumor is quite rare. Shields reports only 61 patients in 26 years of practice.
Etiology: Uncertain, thought to be a choristoma; ~1/5 of the cases are however bilateral.
Clinical Findings: The typical presentation is that of a young (25 years is approximate mean age) white woman (at least 2/3 are in women) with a characteristic slightly elevated lesion that appears yellow to orange and has well-defined margins often with calcification in the juxtapapillary choroid. Choroidal osteomas typically enlarge slowly over many years. If the tumor involves the macula, vision is generally impaired. Subretinal neovascularization is a common complication of macular choroidal osteoma (~30%). Both choroidal osteoma and hemangioma may mimic a choroidal melanoma clinically and should, therefore, be included in the differential diagnosis of choroidal melanoma. About 1/5 of the cases are bilateral. The complication of neovascularization appears to be associated with decalcification of the tumor and visual loss.
Histopathology: A single clinicopathologic report has been published by Williams et al. and was mistaken for a melanoma. The tumor is composed of unremarkable-appearing compact bone located in the peripapillary choroid. The intratrabecular spaces are filled with a loose connective tissue containing large and small blood vessels, vacuolated mesenchymal cells, and scattered mast cells. The bone trabeculae contained osteocytes, cement lines, and occasional osteoclasts (expected with decalcification). The images we provide here show bone (number 1) in the choroid, but the clinical history was not known in the case. The overlying retina shows severe degenerative changes (arrow 2) and osteocytes are seen in lacunar spaces (arrow 3). A line showing the interface of calcified and non-calcified osteoid is evident (4). A hint of lamellae formation is seen especially to the right of number 3.
At higher magnification, one can appreciate the location in the choroid with adjacent melanocytes (number 6). The retinal pigment epithelium (number 5) is also visible in an adjacent section. The retina is detached (number 2). Note the absence of osteoblastic rimming.

Treatment: Some recommend laser therapy of neovascularization in small osteomas or osteomas with an enlarging rim, with the understanding that laser therapy may accelerate decalcification and that visual acuity after laser therapy is quite poor despite regression of the tumor. The rationale for treatment is if the tumor is small it is possible that the residual damage will be mitigated if treated when the lesion is tiny. There are reports of stabilization of a choroidal osteoma with transpupillary thermal therapy.
Prognosis: About half of the patients will lose vision and over half have poor visual acuity as the final outcome.

References:

Shields et al
Shukla D et al

Friday, January 26, 2007

Eccrine Hidrocystoma or Ductal Cyst

Definition: benign cystic lesion of the eyelid characterized by cuboidal epithelium and fluid content.
Incidence/ Prevalence: Although not well studied eccrine hidrocystomas account for less than 5% of all eyelid biopsies.
Etiology: The morphology suggests the cysts are ductal in origin, hence the more common name ductal cyst.
Clinical Findings: The mean age is about 59 years with a range from 39-91 in one series (Singh et al). The patient usually present with a single clear cystic tumor that is close to but not involving the upper eyelid margin. The lesions are usually solitary (71%), and located on the upper eyelid (2/3). Almost all are less than a cm in size and 1/3 are less than 1 mm. About 90% of ductal cysts are close to the eyelid margin but generally don’t involve the margin. Proximity to the lid margin distinguishes the ductal cyst from the apocrine hidrocystoma. The lesion may be pigmented although this occurs in less than 10% of ductal cysts. The lesions may be bilateral although this is also rare.
Gross: The lesion is cystic, contains clear fluid and lined by a smooth surface with occasional infoldings. In the accompanying image one can see a clear cyst (magnified of course) demarcated by the black arrows. There is surrounding fibrous tissue as this lesion was shelled out from the conjunctival surface. Ductal cysts may arise from the conjunctiva as well as from eyelid. The cysts contain clear fluid as opposed to keratinaceous material that is often seen in epidermal or sebaceous types of cysts.

Histopathology: The classic description features a cystic cavity (number 1) with lightly eosinophilic staining material in the center. There is perhaps eosinophilic proteinaceous contents here although it is poorly defined (arrows 5). Eccrine hidrocystoma is lined by a double layer of cuboidal cells (arrows 2 and 3). The inner layer facing the cyst shows some minor budding toward the lumen arrow 2).




















However, often the basal layer is actually flattened evidence that this cyst is of ductal origin. Note in the figure that the surface of the biopsy specimen is keratinized stratified squamous epithelium. This finding may seem trivial but indicates that the location is skin at least slightly away from the eyelid margin; sometimes pathologists are not given that information. Also note just for fun, the pigmentation of the basal layer, extravasated erythrocytes and free pigment in the superficial dermis in combination with a mild perivascular inflammatory infiltrate. Not all eccrine hidrocystomas have a uniform or consistent lining we have seen parts of the cyst lined by stratified squamous epithelium.
Treatment: Complete excision is generally performed without recurrence.
Reference
1. Singh et al. Eye 2005 19;77-9.

Wednesday, January 24, 2007

Chalazion or Lipogranulomatous Inflammation

Definition: a localized lipogranulomatous inflammatory condition that involves sebaceous glands of the eyelid presumably due to duct obstruction.
Incidence/ Prevalence: One of the most common lesions of the eyelid.

Etiology: The cause of the duct obstruction is an important issue. Chalazia usually result from obstruction caused by non-infectious obstruction but more importantly may be caused by neoplastic conditions especially sebaceous carcinoma. Also infections, particularly staphylococcus infection of the meibomian glands may cause chalazion.
Clinical: The presentation is usually indolent and painless and may manifest as a thickening in the area of the tarsus or an area of redness. The chalazion may become visible as swelling proceeds to the skin surface (white arrow #1 in image above). The lesion may rupture or even appear as a polypoid mass (white arrow #2). At the time of removal, chalazia may range from a thick viscous yellow material to a fibrous nodule (old lesions).
Histopathology: The lesion features lipogranulomatous inflammation, the proper diagnosis given by pathologists for this lesion. Chalazion is a clinical diagnosis. In paraffin sections, clear circular empty spaces (1 in the figures) presumably represent lipid that has dissolved in the organic solvents during processing. The clear spaces are surrounded by nodular collections of epithelioid histiocytes (2 and arrows). The epithelioid histiocytes have bean shaped, lightly staining nuclei with abundant pink vacuolated cytoplasm. The areas around the granulomata show chronic inflammation with a mixture of inflammatory cells including, neutrophils, lymphocytes, plasma cells, and eosinophils. Occasionally multinucleated giant cells result from the syncytial coalescence of the epithelioid histiocytes (number 4, below and near number 2 above). Obviously this histologic appearance may be produced by many infectious organisms including tuberculosis, cat scratch disease as well as sarcoidosis, and other conditions. Special stains for organisms (Ziehl-Neelsen, Gram, PAS, and GMS stains) are generally performed in cases that show lipogranulomatous inflammation.

Indications for Performing Histologic Sections of Chalazia: Many ophthalmologists do not send specimens from the initial chalazia removed for the first time. However, this may be difficult to explain to the patient when an underlying tumor such as sebaceous carcinoma is discovered sometime later and is now much larger than the initial lesion. The cost of obtaining the histology (which is minimal compared to the procedure costs) does not outweigh the potential risk of missing a treatable lesion. Too many sebaceous carcinomas are diagnosed from “recurrent chalazia” in lesions that were previously excised and discarded.
Treatment: Most ophthalmologists will initially treat patients with warm compresses as many chalazia will resolve in time without surgical curetting. Antibiotics should be given for chalazia caused by infection. Obviously complete excision is indicated for those chalazia caused by neoplasms.