Histology/Pathology

Question 1

Organelle responsible for release and reuptake of calcium ions during muscle contraction:

Golgi apparatus
Smooth ER
Rough ER
Myofilaments

Answer 1

1. Golgi apparatus - stores, packs, and transports proteins and lipids
2. Smooth endoplasmic reticulum
3. Rough endoplasmic reticulum - protein synthesis
4. Myofilaments - key regulators of contraction in skeletal
   and cardiac muscle

Question 2

Connective tissue cell with the characteristic “signet ring” appearance:

A. Krukenburg tumor
B. Macrophage
C. Adipocyte
D. Lipoblast

Answer 2

A. Krukenburg tumor
- tumor with signet ring differentiation
B. Macrophage
- white blood cell w/ pseudopods - phagocytosis
C. Adipocyte
D. Lipoblast
- precursor cell for adipocyte; seen in liposarcoma
Adipocyte: “signet ring” - characteristically have abundant multivacuolated clear cytoplasm and hyperchromatic, indented nucleus

Question 3

An 18-year old male is admitted because of a fracture sustained after a fall. X-ray showed elevation of the adjacent periosteum, with a soft tissue component described as having a “sunburst” appearance. Bone biopsy showed hyperchromatic, pleomorphic spindle cells forming an osteoid
matrix. The most likely diagnosis is:

A. Ewing Sarcoma
B. Chondrosarcoma
C. Osteosarcoma
D. Giant Cell Tumor

Answer 3

C. Osteosarcoma

A. Ewing Sarcoma (2nd m/c bone sarcoma in children; t(11:22) EWS-FLI1 fusion gene) - XR: lytic lesions with onion-skin deposition of reactive bone
- B: small, round blue cells in scant fibrous stroma, Homer Wright rosettes

B. Chondrosarcoma (2nd m/c malignant bone tumor; age >40)
- XR: lytic lesion with popcorn calcification, moth-eaten appearance (in high-grade tumors) - B: anaplastic, chondrocytes with varying cellularity, mitosis and atypia

C. Osteosarcoma (m/c bone tumor)
- XR: periosteal lifting (Codman triangle), infiltrative borders (sunburst appearance) - B: hyperchromatic, pleomorphic spindle cells forming lace-like pattern (diagnostic)

D. Giant Cell Tumor (benign, locally invasive; age 20-40) - XR: soap-bubble appearance
- B: multinucleated; giant cells with fibrous stroma

Question 4

This type of breast carcinoma shows malignant cells arranged in fronds of fibrovascular tissue lined by tumor cells, forming leaf-like structures:

A. Ductal
B. Lobular
C. Mucinous
D. Papillary

Answer 4

A. Ductal
B. Lobular [Lobular Carcinoma originates from terminal ductules of the lobule; high propensity for bilaterality, multicentricity & multifocality]
C. Mucinous [colloid carcinoma; bulky, mucinous tumor; cut surface: glistening, glaring, & gelatinous]
D. Papillary [Lowest frequency of axillary nodal involvement]

Question 5

What type of breast carcinoma shows cells arranged in clusters and small islands of cells within large lakes of mucin?
A. Invasive ductal
B. Invasive lobular
C. Colloid 
D. Papillary

Answer 5

C. Colloid
Lobular
• Cells fairly uniform in size and appearance
• Non-cohesive infiltrating cells with intracytoplasmic mucin
droplets, signet ring cells
• 2 prominent patterns:
o Indian file pattern 
o Targetoid pattern

Papillary
• fronds of fibrovascular cores lined by tumor cells Colloid /

Mucinous
• gray-blue gelatinous cut surface, tumor cells are arranged in clusters and small islands of cells within large lakes of mucin
• pushing or well circumscribed borders Tubular
• consists of exclusively well-formed tubules
• sometimes mistaken for a benign sclerosing lesion

Medullary
• circumscribed or pushing borders (like Mucinous CA)
• syncytial growth pattern, high grade nuclei, prominent lymphoid infiltration

Question 6

A mass in the sigmoid colon was seen on colonoscopy of a 60-year-old patient with GI bleeding. Biopsy showed back-to-back glands lined by pleomorphic, hyperchromatic nuclei with scant cytoplasm. What is the diagnosis?
A. Squamous cell carcinoma
B. Small cell carcinoma
C. Adenocarcinoma 
D. Leiomyosarcoma

Answer 6

C - Adenocarcinoma

Adenocarcinoma
• Malignant tumor glands invading the stroma
• Back to back glands with no stroma in between, cribriform pattern
of glands lined by hyperchromatic nuclei and prominent nucleoli
Squamous cell carcinoma
• Islands of malignant squamous cells already invading the stroma
• Grade I: well differentiated - with keratin pearls
• Grade III: poorly differentiated - no keratin pears
Small cell carcinoma
• Cells smaller than SCCA, with scanty cytoplasm
• Look like small cell / oat cell CA of the lung, but differs in being (+)
high risk HPV
• Neuroendocrine origin confirmed by immunohistochemistry
(chromogranin, synaptophysin, CD56)
Leiomyosarcoma
• Pleomorphic, hyperchromatic nuclei, irregular borders
• Very large cells, presence of mitotic folds, and dark staining
• Tumor necrosis AND high mitotic activity OR atypia are present; If
no tumor necrosis, three is high mitotic activity AND high or moderate

Question 7

A 30-year-old female presents with a breast mass. Biopsy of the mass showed a proliferation of the intralobular stroma compressing the ducts and ductules into slit- like spaces. What is the diagnosis?
A. Fibroadenoma
B. Phyllodes tumor
C. Invasive ductal carcinoma
D. Ductal papilloma

Answer 7

A. Fibroadenoma

In Fibroadenoma, there is proliferation of the ducts as well as the stromal elements. Stromal proliferation compresses the ducts from round to oval shape to slit-like structures.