APCON 2009 Kolkata
NATIONAL
PATHOLOGY QUIZ – 1
Answers
Q 1: Devil
facial Tumor disease (DFTD). A transmissible tumor occurring in the Tasmanian
devil
We start this year’s quiz with a fascinating disease: something new in neoplasia that most of us have not yet started teaching our undergrads.
This disease occurs in the carnivorous marsupial - Tasmanian Devil (Sarcophilus harrisii). It is an undifferentiated malignant round cell tumor, probably of neuroectodermal origin.
The surprising thing about this tumor is that it is transmitted from one animal to other by contact – biting and fighting – which the devils frequently indulge in. It is not transmitted through a virus; but the tumor cells themselves are infectious.
The chromosomes in these tumors have undergone a complex rearrangement that is identical for every animal studied. In other words the tumor cells do not belong to the host but is like an allograft. The low genetic diversity among the Tasmanian devils has been blamed for the emergence of such a tumor that is not rejected by the host immune system.
This is a relatively new tumor that has emerged in the recent years. It is fatal and threatens extinction of the unique Tazzy devils.
The other well defined transmissible tumor is Canine transmissible
venereal tumor (CTVT) described by Russian veterinarian MA Novinsky (1841–1914)
in 1876, when he demonstrated that the tumor could be transplanted from one dog
to another by infecting them with tumor cells. This is a histiocytic tumor that
is much older, having originated 200 to 2500 years ago and consequently milder
in behavior, frequently undergoing spontaneous remission. CTVT cells have fewer
chromosomes than normal cells and are very different in appearance from normal
dog chromosomes. Also, a
Canine transmissible tumor on the Dog Penis & its
histology
Correct answers: 36.6%
Links
- Pathology of Devil Facial Tumor Disease
- DFTD and loss of MHC diversity
- Infectious Cancer Cells
- National Geographic video of the Tasmanian Devil
Q 2: Acute monoarthritis due
to Maltese cross-like lipid crystals
With the history provided, I suppose it is safe to guess
that the picture is of synovial fluid under polarized light. There are
birefringent crystals with a particular shape. See below the resemblance of
these crystals (Left – from the picture given to you) and the typical Maltese
cross (Right): symbol of the order of Christian warriors known as Knights of
Malta and through them identified with the Mediterranean
Many of you have diagnosed this as calcium oxalate crystals, no doubt by its resemblance to the bipyramidal envelope so commonly seen in the urine. Typical envelope shaped (also referred to as Maltese cross by some) crystals tend to occur with Calcium oxalate dihydrate or weddelite. But these are poorly birefringent unlike the monohydrate form of oxalate which has an elongated and pointed shape.
Calcium Dihydrate crystals in urine. They are poorly
birefringent.
Talc from surgeon’s gloves can have a Maltese cross birefringence. But they tend to be larger and more spherical. Anyway they are unlikely to be associated with acute arthritis. This patient had crystals of the same appearance in repeated taps. There were also many neutrophils.
Maltese-cross-appearing lipid spherules in the synovial fluid of patients with acute Monorthritis has been well described. The clinical significance of these spherules is obscure. They might be a side effect of the arthritis, originating from synovial fat released into the knee joint or from membrane lipids of lysed cells, or they may initiate the arthritis. This possibility is supported by animal experiments.
Correct answers: 30.8%
Links
Q 3: Focal Segmental Glomerulosclerosis in Cholesterol embolism
Lo and behold! Like a rare planetary conjunction you have two lesions captured in close proximity in a single photograph. Though this is exceedingly rare, the individual lesions are not. Many of you have diagnosed either one of them earning half credit; but none have managed the full score. Mind block; I guess.
The vessel shown has linear and angulated clefts suggestive of cholesterol. For the doubting Thomases, here is another picture from the serial section.
According to one study, FSGS was observed in as many as 15 out of 24 biopsies done for cholesterol atheroembolic renal disease.
Correct answers: 23.3%
Links
1. FSGS in Cholesterol atheroembolism
2. Perspectives on Ischemic Renal Disease
Q 4: Lipoid Proteinosis
Sorry; it is not laryngeal amyloidosis as many have suggested. That would have been too easy – isn’t it? The sweat glands are very clearly seen. There is an eosinophilic hyaline material all around the eccrine glands as well as around blood vessels. The material can also be seen as a thin line beneath the epidermis. Here is the PAS stain.
Lipoid proteinosis, also known as 'Hyalinosis cutis et mucosae' or Urbach-Wiethe disease is an autosomal recessive disorder in which there is deposition of hyaline material in the skin and mucosal sites. Thickened skin lesions including the characteristic beaded papules along the eyelid margins and tongue enlargement are common. Laryngeal deposition leads to hoarseness.
The disease is now known to be caused by mutations of the ECM-1 gene.
Correct answers: 39.5%
Links
1. Lipoid Proteinosis (OMIM entry)
2. Molecular defect in Lipoid Proteinosis
Q 5: Pulmonary interstitial emphysema
The pictures show large empty spaces in the lung, mostly around and in close proximity to the blood vessels. These are pseudocysts without an epithelial lining. Several giant cells can be seen lining the cysts (see last picture). This is similar to the more familiar pneumatosis intestinalis and is a foreign body reaction to air.
Pulmonary interstitial emphysema is an air leak syndrome to which pre-term infants with history of assisted ventilation are particularly prone. It can be acute where the cysts are smaller and without tissue reaction or persistent with larger cysts and giant cells as in this case.
Correct answers: 3.5%
Links:
1. Pulmonary air leak
syndromes
2. Pubmed abstracts with links to full text
Q 6: Filigree pattern of osteoid in
osteosarcoma
Yes, it does resemble fungal hyphae as some of you have suggested. But a closer look reveals an interweaving filigree pattern that is different. This is partly mineralized osteoid and this kind of extremely thin trabeculae not lined by normal osteoblasts is very typical of osteogenic sarcoma.
For benefit of the skeptics, here are pictures from the same tumor permeating normal bone and soft tissue
.
Correct answers: 5.8%
Links:
1. A review of bone forming tumors
Q 7: CD 117 in Cutaneous mastocytosis and
GIST
Remember, the question was to name the antibody – in singular. This clearly implied that the same antibody was used in both the cases. I deliberately used a low power for the cutaneous lesion: after all, it is a Quiz! Here is the higher power
Correct answers: 53.5%
Links:
1. CD 117
Q 8: Fibrolamellar carcinoma, liver
First of all, it is a needle biopsy. There are groups of large cells with abundant eosinophilic cytoplasm separated by broad bands of fibrosis. So the special stain must be a trichrome for collagen (It is not extracellular mucin, because there is no blue color in the H&E section). The collagen fibers are arranged in a rather parallel manner.
Elementary my dear Watson?
Actually not. Without higher power pictures, it is a matter of good guesswork and lots of luck.
Correct answers: 9.3%
Links: