Endocrine Disorders

Hypopituitarism

• Growth hormone deficiency may cause proportional dwarfism due to epiphyseal growth retardation or delayed skeletal maturation
• Associated with adiposity and hypogonadism
• Epiphyses remain unfused
• There is danger of epiphyseal slipping at the hip or knee, especially in adiposogenital syndrome 

Treatment

• Removal of craniopharyngioma
• Hormone replacement therapy

Hyperpituitarism

• Acidophil cell hypersecretion results in skeletal overgrowth 
• Effects vary according to the age of onset
• Gigantism : GH stimulates epiphyseal growth
  • Patients are excessively tall
  • Often with hypogonadism and mental retardation
  • Slipped epiphyses may occur
• Acromegaly : GH stimulated apophyseal growth and hypertrophy of articular cartilage
  • Adult onset
  • Jaw enlargement
  • Thickening of the skull
  • Hands and feet are big 
  • Long bone ends are markedly thickened with osteoarthritis being common

Cushing’s Syndrome

• May be due to hypersecretion of adrenal cortex
• More commonly due to corticosteroid therapy
• Characteristic obesity of face and trunk 
• Generalised osteoporosis

Cretinism

• Congenital thyroid deficiency
• Severely dwarfed 
• Mentally retarded
• Irregular epiphyseal ossification may be mistaken for AVN
• Changes can be prevented by early treatment with thyroid hormone

Heterotopic calcification

Definition


Deposition of Ca salts in tissues other than osteoid or enamel

There are 2 types of heterotopic calcification

1. Dystrophic calcification : deposition of Ca salts in dead or degenerate tissue 
   1. Plasma levels of Ca and PO4 are normal 
   2. Local conditions are thought to be most important
2. Metastatic calcification : precipitation of Ca salts in apparently normal tissues 
   1. General disorder of Ca/ PO4 metabolism
   2. There is usually hypercalcaemia

Dystrophic Calcification

• Calcification in dead tissue
  • Caseous material
    • TB: seen in chronic abscess, healed Ghon focus, nodes
    • Healed lesions of Histoplasmosis and Coccidiomycosis
  • Dead parasites
    • Hydatid
    • Schistosome
    • Cysticercosis
  • Fat necrosis
  • Infarcts
  • Thrombi in veins form phleboliths
  • Haematomata, esp. when the haematoma is in close association with bone in myositis ossificans there is calcification and subsequent ossification of the haematoma in the muscle
• Calcification in degenerated tissue
  • Scars
  • Chronic inflammatory granulation tissue
  • Atheroma this is intimal calcification
  • Monckebergs sclerosis : calcification of the media
  • Senile degenerate tissue
    • Costal cartilages in the elderly
    • Pineal gland after middle age
    • Dura in old age
    • Supraspinatus tendon
  • Calcinosis Universalis 
    • A rare manifestation of systemic sclerosis 
    • Widespread calcification of the skin, subcutaneous tissue, muscles and tendons
  • CREST syndrome : Calcification of the finger pulps
  • Tumoral calcinosis
    • Large calcareous swellings in the subcutaneous tissues near the larger joints 
    • Seen most often in black Africans
  • Chondrocalcinosis
    • Deposition of Ca pyrophosphate crystals in cartilage
    • Associated with
      • Ochronosis
      • Haemochromatosis
      • Hyperparathyroidism
      • Gout
    • May be an idiopathic isolated condition
  • Heterotopic ossification can occur at any site of dystrophic calcification

Metastatic calcification

• Disordered Ca/PO4 metabolism
• Usually due to hypercalcaemia
• In renal osteodystrophy the cause is excess PO4
• Calcification occurs in
  • Kidney
    • Esp. around the tubules = nephrocalcinosis
    • May lead to renal failure
    • May get calculi in pelvis or ureter
  • Lung : Ca deposited in alveolar walls
  • Stomach : Ca deposition around the fundal glands
  • Blood vessels
  • Cornea

Myositis Ossificans

Extraskeletal ossification can occur in muscle or other soft tissue

Classification

1. Myositis Ossificans Progressiva (= Fibrodysplasia ossificans progressiva)
   • Autosomal dominant
   • Progressive laying down of bone in tendons, aponeuroses, fascia 
   • Body may become completely rigid
   • Associated with microdactyly and monophalangy of the big toe
2. Traumatic localised myositis ossificans
   • A haematoma forms in fascial planes or within muscle.
   • Granulation tissue then forms around and invades the heamatoma.
   • Primitive mesenchymal cells in this granulation tissue mature into osteoblasts and proliferate to form bone
   • Pathology: peripheral mature and central immature zones ( = the zoning phenomenon).
     • Mature zone has well oriented and mature trabecular bone.
     • Immature zone has a spindle cell proliferation and a disorderly arrangement of cells.
     • Between these zones an intermediate zone shows chondral differentiation
     • Immature zone mimics the histological appearance of a sarcoma due to the spindle cell proliferation, high mitosis rate, etc.
3. Non traumatic localised myositis ossificans
   • Seen in burns patients and patients with neurological injury