Page 139 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-54 Rashes

SYSTEMIC FINDINGS OF OCHRONOSIS

Pigmentation,
calcification, and
ossification of
intervertebral
discs and fusion
of vertebrae

Typical narrowing and calcification of
intervertebral discs without involvement
of sacroiliac joints

Ochronotic pigmentation
of cartilage on femoral
Femoral condyle head; underlying bone
normal

Patella
Characteristic posture
in advanced ochronotic
OCHRONOSIS (Continued) spondylitis: kyphosis,
rigid spine, flexed knees,
Eburnation wide base
tympanic membrane and the stapes, incus, and malleus
bones of the inner ear. The patient may suffer from Osteochondroma
tinnitus.
With time, the skin in various regions begins to
become hyperpigmented. This occurs first and fore- Semilunar cartilage
most in the areas with a high concentration of sweat Ulcer-
glands. The axillae and the groin are noticeably affected. ation
The excessive homogentisic acid is secreted in the
sweat, and the pigment discolors the surrounding skin.
The cheeks are also prominently affected.
The most disabling aspect of this disease is the depo- Exposure of knee joint: pigmentation, eburnation,
sition of homogentisic acid in the fibrocartilage and and ulceration of cartilages; osteochondroma
hyaline cartilage. This leads to severe degenerative joint with pedicle to synovial lining
disease at an early age. The pigment alters the cartilage
and makes it brittle and friable. The cartilage begins to Pigmentation of endocardium
fragment and disintegrate and can get embedded in the
synovial tissue, causing synovial polyps. The interver-
tebral disks become severely pigmented and begin to
calcify because of the massive destruction of the carti- to the accumulation of homogentisic acid in various replacement increase flexibility and range of motion
lage. The disks are destroyed, causing a severe reduc- tissues throughout the body and the subsequent clinical and help to decrease morbidity. Some researchers advo-
tion in the patient’s height, as well as chronic pain and manifestations. cate a diet low in phenylalanine and tyrosine, although
rigidity of the spine. Eventually, the heart, prostate, Histology: The findings on skin biopsy are pathog- the success of this approach is anecdotal at best. The
aorta, and kidneys all show evidence of ochronosis. nomonic for ochronosis. Large ochre bodies are found National Institutes of Health is currently studying an
Pathogenesis: Ochronosis is the result of an auto- within the dermis. These are obvious on low-power inhibitor of the enzyme 4-hydroxyphenylpyruvic acid
somal recessive inherited disorder that causes the microscopy and can be used to confirm the diagnosis. dioxygenase, which would decrease the production of
affected patient to be deficient in the enzyme homo- Treatment: No known cure is available, and there homogentisic acid and theoretically help to decrease
gentisic acid oxidase. This deficiency, over time, leads is no effective therapy. Physical therapy and joint joint destruction.

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