MISCELLANEOUS

PLEOMORPHIC ADENOMA

A 40 year old man presented with a right neck swelling. Surgery was performed.
 
1.    What are your differential diagnoses?
 
a.    Pleomorphic adenoma.
b.    Brachial cyst.
c.    Cystic hygroma.
d.    Pharyngeal pouch.
e.    Sternocleidomastoid tumor.

2.    What are the clinical manifestations of this condition?
 
Slow-growing, smooth, painless swelling. 

3.    What are the surgical requirements for the treatment of this condition and why?
 
There may be small nodules attached to the main tumor which can be left behind at surgery if the main tumor is shellout without a surrounding zone of normal salivary gland. This can lead to apparent recurrence of the tumor. Therefore, adequate margins of resection is required during surgery. However it may be difficult because of the need to spare the facial nerve, which runs between the deep and superficial parts of the parotid.

4.    Why is surgery indicated?
 
Malignant transformation occurs in 10% of pleomorphic adenomas of more than 15 years' duration, usually in the form of adenocarcinoma or undifferentiated carcinoma.

BRAIN ABSCESS

1.    What are the gross morphological features?
 
The organ shown is the brain. There is a cavity 3 - 4cm in diameter in the left basal ganglia, filled with an ill-defined, soft, brown material which is likely to be pus. The borders of the cavity are lined by a red amorphous material sequestered from the brain white matter and this may be composed of fibrovascular tissue. The surrounding brain parenchyma appears to be swollen, congested and soft. 

2.    What are the histological features?
 
There is a central region of liquefactive necrosis and a fibrous capsule surrounded by reactive gliosis with proliferation of astrocytes and their processes forming a scaffolding around the capsule. 

3.    What are the clinical manifestations of this condition?
 
a.    Signs of raised intracranial pressure: vomiting, headache, papilloedema, bradycardia and hypertension.
b.    Focal neurological deficits depending on the site, e.g. hemiparesis, personality changes, visual field defects.
c.    Seizures.
d.    Swinging fever.
e.    Coma.

4.    What pathological process does this illustrate?
 
Liquefactive necrosis: liquefaction completely digests the dead cells. The end result is transformation of the tissue into a liquid viscous mass.

5.    What are the common etiologic agents involved?
 
Streptococci and staphylococci.

6.    What are the causes?
 
a.    Secondary to meningitis.
b.    Local extension from sepsis in the middle ear or mastoid cavities.
c.    Hematogenous: associated with bacterial endocarditis, cyanotic congenital heart disease, and bronchiectasis.
d.    Trauma following open injuries to the CNS. 

7.    What are the two causes of death?
 
a.    Cerebral herniation due to raised intracranial pressure.
b.    Abscess rupture leading to sagittal sinus thrombosis and subsequent brain infarct.
c.    Spread of inflammation to the brainstem. 

8.    What is your immediate management?
 
To decrease ICP and avert secondary injury:
 
a.    Elevate head of bed to 30 - 40 degrees.
b.    Hyperventilate the intubated patient.
c.    Osmotic agents, e.g. mannitol.
d.    Definitive: craniotomy or burr hole followed by surgical drainage of abscess.

CONGESTIVE SPLENOMEGALY

1.    What are the causes of this condition?
 
a.    Systemic or central venous congestion encountered in cardiac decompensation involving the right side of the heart.
b.    Intrahepatic derangement of portal venous drainage, as occurs in various forms of cirrhosis of the liver.
c.    Obstruction to the extrahepatic portal vein and splenic vein in spontaneous portal vein thrombosis.

2.    What complications can arise?
 
a.    Pain and discomfort.
b.    Mechanical rupture.
c.    Hypersplenism with subsequent complications of pancytopenia - anemia, easy bleeding, recurrent infections. 

OSTEOSARCOMA

2.    What are the histological and radiological features?
 
Histology: The malignant osteoblasts produce osteoid, some of which becomes mineralized - anaplastic cells found within lacunae of osteoid. There is marked hyperchromasia, abnormal mitoses and bizarre looking giant cells in the fibroblastic component. 
 
Radiology: X-ray shows a combination of bone destruction and formation. The medulla contains areas of rarefaction or density. The cortex is usually perforated and a soft-tissue shadow may be seen. There is subperiosteal new bone formation and streaks of calcification in the adjacent soft tissues - the 'sunray' appearance.

3.    What are the common sites affected?
 
a.    Lower end of femur.
b.    Upper end of tibia.
c.    Proximal humerus. 

4.    Who is commonly affected?
 
The incidence is highest between the ages of 10 and 20 years, but a second peak occurs after 50 due to malignant change in Paget's disease.

5.    Where does the lesion come from?
 
The tumor originates in the medullary cavity close to the metaphyseal plate and spreads extensively within the medullary cavity, eventually eroding through cortical plate and extending into soft tissue.

CHONDROSARCOMA

Chondrosarcomas are slow-growing tumors that often reach a large size, expanding the bone and eventually breaking through the periosteum into surrounding soft tissue. Although malignant, they metastasize very late in most cases, the majority being low-grade well-differentiated tumors. 

GIANT CELL TUMOR

Giant-cell tumors of bone are osteolytic lesions that occur in young and middle-aged adults, generally being more common in women. The bone is replaced by a mass of large multinulceated giant cells resembling large osteoclasts, which are embedded in a supporting spindle-celled stroma. The lesions expand into the metaphysis and, with enlargement, may erode the cortical bone. However, they rarely penetrate the periosteum or articular cartilage. These locally aggressive tumors are difficult to treat because of frequent recurrence at the site of inadequate local excision.  

MULTIPLE MYELOMA

Myelomas arise from plasma cells of the bone marrow. They are usually multiple from the start but occasionally a large tumor presents as a solitary bone lesion - a 'plasmacytoma'.
 
The patient, aged 45 - 65, presents with weakness, bone pain or a pathological fracture. The pain is constant and backache is common, sometimes with root pain and occasionally paraplegia. Anemia, cachexia and chronic nephritis are present. There is a high ESR. The usual cause of death is renal failure.
 
X-rays may show multiple punched-out defects in more than one bone. Vertebral involvement may cause compression fractures. Urinalysis shows Bence-Jones protein.

THYROID: FOLLICULAR ADENOMA

A 40-year-old woman presents with a neck mass.
 
1.    What is your diagnosis?
 
Thyroid follicular adenoma

2.    What are the reasons for your diagnosis?
 
It is a solitary nodule well demarcated from the adjacent parenchyma by a well-defined fibrous capsule. 

3.    What pre-op procedures are needed?
 
Fine needle aspiration biopsy is frequently used to evaluate the suspected adenomas before surgical excision.

4.    What are the clinical manifestations?
 
a.    The patient is euthyroid.
b.    The nodule is palpable and visible, smooth, usually firm and not hard, painless and moves freely on swallowing.

5.    Why does the patient complain of sudden pain and swelling?
 
It is due to hemorrhage into the adenoma. However, suspicion of a carcinoma should be raised.

6.    What is the pathogenesis?
 
Somatic mutations in some of the components of TSH receptor signaling system cause chronic stimulation of the cAMP pathway, generating cells that acquire a growth advantage. This results in clonal expansion of specific epithelial cells, leading to the formation of autonomous monoclonal thyroid adenomas.

7.    What complications can it give rise to?
 
a.    Toxic adenoma with development of secondary thyrotoxicosis.
b.    Development of carcinoma from nodule.

THYROID: PAPILLARY CARCINOMA

The specimens on the left and right are thyroid papillary and follicular carcinomas respectively.
 
1.    What are the predisposing factors for thyroid cancer?
 
a.    Exposure to ionizing radiation during the first two decades of life.
b.    Thyroid diseases: nodular goitre and Hashimoto thyroiditis.

2.    What are the histological features of papillary carcinoma?
 
a.    Fibrous capsule is breached by infiltration of tumor into normal thyroid tissue.
b.    Form: complex papillary structures, each composed of a narrow stromal core covered with a layer of glandular epithelium.
c.    Stromal cores contain small calcified laminated bodies called psammoma bodies.

3.    What is its clinical course?
 
Most papillary carcinomas present as asymptomatic thyroid nodules, but the first presentation may be a mass in a cervical lymph node. The carcinoma, which is usually a single nodule, moves freely during swallowing and is not distinguishable from a benign nodule. Hoarseness, dysphagia, cough, or dyspnoea suggests advanced disease. Prognosis is generally excellent. 

MULTINODULAR GOITRE

A 70-year-old lady presents with a neck mass and pain. Surgery was done. 
 
1.    What are the possible diagnoses?
 
a.    Multinodular goitre: irregular multinodular enlargement of the entire thyroid.
b.    Follicular adenoma / carcinoma: focal nodular enlargement with the thyroid.
c.    Hashimoto's disease: symmetrical nodular firm enlargement of whole thyroid.
d.    Grave's disease: symmetrical diffuse enlargement of thyroid.

2.    What are the indications for surgery?
 
a.    Cosmetic deformity.
b.    Esophageal compression with dysphagia.
c.    Obstruction of superior vena cava. 
d.    Tracheal compression.
d.    Hemorrhage into goitre causing pain.
e.    Thyrotoxicosis.

3.    What are the postoperative complications?
 
a.    Respiratory obstruction due to laryngeal edema. 
b.    Parathyroid insufficiency and hypocalcemia.
c.    Recurrent laryngeal nerve paralysis.

HASHIMOTO’S THYROIDITIS

This symmetrically small thyroid gland demonstrates atrophy. This patient was hypothyroid. This is the end result of Hashimoto's thyroiditis. Initially, the thyroid is enlarged and there may be transient hyperthyroidism, followed by a euthyroid state and then hypothyroidism with eventual atrophy years later
 
1.    What are the histological features?
 
a.    Infiltrate of lymphocytes, plasma cells and macrophages associated with prominent germinal centers.
b.    Parenchyma is paler than normal with interstitial fibrosis.
c.    Abundant eosinophilic granular cytoplasm in residual follicular cells: Hurthle cells.

2.    What is the pathogenesis?
 
It is caused primarily by a defect in the function of thyroid-specific suppressor T cells which results in the emergence of CD4+ helper T cells directed at the thyroid and the production of autoantibodies to various components of the thyroid. The most common autoantibodies are an anti-microsomal antibody and an antibody against thyroglobulin.

3.    What other conditions is it associated with?
 
a.    Systemic lupus erythematosus.
b.    Sjogren syndrome.
c.    Rheumatoid arthritis.
d.    Pernicious anemia.
e.    Type II diabetes.
f.     Graves disease.
g.    Small risk of subsequent lymphoma. 
a.    Respiratory obstruction due to laryngeal edema. 
b.    Parathyroid insufficiency and hypocalcemia.
c.    Recurrent laryngeal nerve paralysis.