Tag Archives: FRCPath multiple choice questions

5 Differences between perilobar and intralobar nephrogenic rests.

Nephrogenic rests are abnormally per­ sistent foci of embryonal cells (still pre­ sent after 36 weeks of gestation) that are potentially capable of developing into nephroblastoma (also called Wilms tumour). The presence of diffuse or multifocal nephrogenic rests is called nephroblastomatosis.

Nephrogenic rests are found in 25-40% of patients with nephroblastoma, and in approximately 1% of term infant autop­sies.

Nephrogenic rests can be found adjacent to nephroblastoma or in the surrounding renal parenchyma. They are classified into perilobar and intralobar types.

Here are 5 differences between perilobar and intralobar nephrogenic rests.

1. LOCATION

Perilobar nephrogenic rests are peripherally located, wheras intralobar nephrogenic rests are randomly intermingled between the renal parenchyma, typically located in the central areas of the lobe.

2. DEMARCATION FROM ADJACENT PARENCHYMA

Perilobar nephrogenic rests are sharply demarcated from the surrounding tissue, whereas intralobar nephrogenic rests are poorly de­marcated, usually infiltrate among native nephrons.

3. STROMA

Perilobar nephrogenic rests have scanty stroma, whereas intralobar nephrogenic rests are and are composed mainly of stromal and epithelial elements.

4. FOCALITY

Perilobar nephrogenic rests are usually multifocal whereas, intralobar nephrogenic rests are mostly unifocal (often single).

5. ASSOCIATED CONDITIONS

Perilobar nephrogenic rests are associated with hemihypertrophy and overgrowth syndromes such as Beckwith-Wiede­mann syndrome. lntralobar nephrogenic rests are associated with Denys-Drash syndrome (which is associated with nephroblastoma, pseudohermaphrodit­ ism, glomerulopathy, and renal failure) and WAGR syndrome (Wilms tumour / nephroblastoma, aniridia, genitourinary anomalies, and mental retardation syn­drome).

PERILOBAR AND INTRALOBAR NEPHROGENIC RESTS HISTOPATHOLOGIC PICTURES.

Difference between perilobar and intralobar nephrogenic rests.

CHENILLE BODIES IN ELASTOFIBROMA

The fragments of elastic fibers seen in elastofibroma are typically arranged linearly, creating a “beads on a string” appearance, and are known as chenille bodies.

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Molecular pathology of ADIPOCYTIC TUMORS

Molecular pathology of ADIPOCYTIC TUMORS – based on WHO 2020 Soft tissue and bone tumors.

LIPOMAS

The pathogenesis of lipomas is related to reactivated expression of the HMGA2 protein, which plays a role in the development of the mesodermal lineage during embryogenesis

  1. ANGIOLIPOMA– The majority (80%) have been reported to have low-frequency PRKD2 mutations.
  2. CHONDROID LIPOMA– is characterized by a recurrent t(11;16) (q13;p13) chromosomal translocation.
  3. SPINDLE CELL/PLEOMORPHIC LIPOMA: is characterized 13q deletions /RB GENE.
  4. MYOLIPOMA: Cytogenetic alterations of the HMGA2 gene have been reported in a few cases

LIPOSARCOMA

  1. Atypical lipomatous tumour/well differentiated liposarcoma: characterized by supernumerary ring and giant marker chromosomes,containing amplified sequence of MDM2
  2. DEDIFFERENTIATED liposarcoma– Amplified MDM2
  3. MYXOID LIPOSARCOMA– Translocations producing FUS-DDIT3 or rarely EWSR1-DDIT3 fusion transcripts are pathognomonic
  4. PLEOMORPHIC LIPOSARCOMA: Complex karyotypes. . The most frequent mutations involve TP53 and NF1.

OTHER ADIPOCYTIC TUMORS

  1. HIBERNOMA: Cytogenetically, almost all hibernomas have breakpoints in chromosome arm 11q, with a distinctive clustering to 11q13.
  2. LIPOBLASTOMA: The most common numerical change is one or more extra copies of chromosome 8, with or without concurrent rearrangement of 8q11-q13

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Molecular pathogenesis of ovarian epithelial tumors.

Molecular progression of serous ovarian tumor. Borderline low and high grade

1.Molecular progression of low grade ovarian serous tumors.
There is data to suggest progression from serous cystadenoma / cystadenofibroma with BRAF / KRAS mutations → SBT (serous borderline tumor) → LGSC (Low grade serous carcinoma) ; however, this is still controversial

2. Molecular progression of high grade serous ovarian tumors.

TP53 alterations in nearly all cases of high grade serous carcinoma

Germline, somatic or promoter hypermethylation (inactivation) of BRCA1 and BRCA2 in ~50% of cases

Some gastrointestinal pathogens and their differentiating features.

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Gastrointestinal pathogens are very common in routine practice. It takes experience and keen observation to differentiate gastrointestinal pathogens from one another. In case of confusion, go with your ‘GUT’ feeling.

Lets look at a few differentiating features of Giardia lamblia, Cryptosporidium parvum and Isospora belli.

  1. GIARDIA LAMBLIA:

Pear shaped trophozoites with 2 ovoid nuclei, present in the luminal surface. They are 10-15 microns in length and 5-9 microns in width.

GIARDIA IS SEEN IN THE LUMINAL SURFACE

CRYPTOSPORIDIUM IS SEEN ATTACHED TO ENTEROCYTES LIKE SMALL BEADS.

2. CRYPTOSOPORIDIUM PARVUM

In tissue biopsies, 2 – 5 μm basophilic round bodies are seen protruding from the apex of enterocytes (“blue beads”) within the cell membrane. Parasites bulge out of apex of epithelial cells

ISOSPORA IS LARGEST AMONG THE THREE. IN CONTRAST TO GIARDIA AND CRYPTOSPORIDIUM – ISOSPORA DOES NOT HAVE AN APICAL LOCATION, INSTEAD LOCATED IN THE TIP OF VILLI.

3. ISOSPORA BELLI

Oocysts are generally ovoid to ellipsoid in shape, range from 10-40µm in length by 10-30µm in width. Cysts are present in PARASITO-
PHOROUS VACUOLE. Does not have an apical location.

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