Lisch nodule, also known as iris hamartoma, is a pigmented
hamartoma
A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended fr ...
tous nodular aggregate of dendritic
melanocyte
Melanocytes are melanin-producing neural-crest, neural crest-derived cell (biology), cells located in the bottom layer (the stratum basale) of the skin's epidermis (skin), epidermis, the middle layer of the eye (the uvea),
the inner ear,
vagina ...
s affecting the
iris
Iris most often refers to:
*Iris (anatomy), part of the eye
* Iris (color), an ambiguous color term
*Iris (mythology), a Greek goddess
* ''Iris'' (plant), a genus of flowering plants
* Iris (given name), a feminine given name, and a list of peopl ...
,
named after Austrian
ophthalmologist
Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders.
An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...
Karl Lisch (1907–1999), who first recognized them in 1937.
The first published use of the term ''Lisch nodule'' was in the ''
New England Journal of Medicine
''The New England Journal of Medicine'' (''NEJM'') is a weekly medical journal published by the Massachusetts Medical Society. Founded in 1812, the journal is among the most prestigious peer-reviewed medical journals. Its 2023 impact factor was ...
'' "Medical Progress" series article of December 31, 1981 (Riccardi VM: Von Recklinghausen Neurofibromatosis. ''N Engl J Med'' 1981;305:1617–27).
These
nodule
Nodule may refer to:
* Nodule (geology), a small rock or mineral cluster
* Manganese nodule, a metallic concretion found on the seafloor
*Nodule (medicine), a small aggregation of cells
*Root nodule
Root nodules are found on the roots of plants, ...
s are found in
neurofibromatosis type 1
Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, e ...
, and are present in greater than 94% of patients over the age of six.
They are clear, yellow-brown,
oval to round, dome-shaped
papules
A papule is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some ...
that project from the surface of the iris. These nodules typically do not affect vision, but are very useful in diagnosis.
They are detected by
slit lamp
In ophthalmology and optometry, a slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope. The lamp facilitates an ...
examination.
Immunohistochemistry
Immunohistochemistry is a form of immunostaining. It involves the process of selectively identifying antigens in cells and tissue, by exploiting the principle of Antibody, antibodies binding specifically to antigens in biological tissues. Alber ...
stains positive against the proteins
vimentin
Vimentin is a structural protein that in humans is encoded by the ''VIM'' gene. Its name comes from the Latin ''vimentum'' which refers to an array of flexible rods.
Vimentin is a Intermediate filament#Type III, type III intermediate filamen ...
and
S-100, and points to an
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the o ...
al origin for the nodules.
[ Their precise origin and structure, however, are still under investigation.]neurofibromatosis type 2
Neurofibromatosis type II (also known as MISME syndrome – multiple inherited schwannomas, meningiomas, and ependymomas) is a genetic condition that may be inherited or may arise spontaneously, and causes benign tumors of the brain, spinal cord, ...
.
See also
* Glaucoma
Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...
* Watson syndrome
Watson syndrome is a rare genetic condition characterised by café-au-lait patches of skin, short stature, pulmonary stenosis, developmental delays, and learning difficulties. Its inheritance is autosomal dominant, and it may also occur with Lisc ...
References
Disturbances of human pigmentation
Ophthalmology
Eye color
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