bones and jts

1. SKIN Sources: Dr. Padla’sppt, Monique’s gross pic, Sec A and Sec B trans

3. Vitiligo Well demarcated zones of pigment loss result from depletion of melanocytes that produce small melanin granules. Note small macules of normal pigment within the patches of vitiligo commonly found in the peri-oral, axilla, groin, knees, elbows and peri-orbital area. not reactive to sunlight

5. Dysplastic Nevus Gross: the periphery is flat (macule) while the center is elevated and dark in color (papule) RED ARROW denotes the dermal papilla which delineates the invasion. GREEN CIRCLE denotes the rete pegs where the nevus can be seen bracket denotes that this is a COMPOUND NEVUS due to the crossing of the melanocytes beyond the dermoepidermal junction

7. Malignant Melanoma Melanoma cells are larger than nevus cells, with irregular and prominent eosinophilic nucleoli. They grow as loose nests lacking the typical features of melanocyte maturation.

10. Malignant Melanoma

12. Langerhans Cell Histiocytosis Immunohistochemical demonstration of CD1a antigen confirms the origin of these mononuclear cells from Langerhans cells Langerhan cells: type of WBC that are phagocytic. They originally come from the bone marrow and upon maturation reside in the skin.

14. Pemphigus initial intercellular edema leads to spongiosis wherein intercellular bridges are pushed or stretched out from each other. Fluid accumulation leads to a fishnet like appearance. This is more likely to rupture

16. Bullouspemphigoid Not likely to rupture because blister is located subepidermally

17. Bones, Joints, and Soft Tissues Sources: Dr. Padla’sppt, Monique’s gross and histopic, Sec A and Sec B trans , Armi’s notes

19. Bone in the process of repair Osteoblast: secretes osteoid matrix which is initially soft; after 2 weeks, it becomes mineralized and becomes lamellar bone Lamellae: layers connected by canaliculi Process depend on application of forces or pressure; if without pressure, bone is resorbed by osteoclast Note: osteoprogenitor cells

21. Note osteoclasts intermingled with osteocytes Osteoclasts acidify environment for bone resorption Calcium hydroxyapatite is broken down and reused by osteoblasts

23. Paget’s disease of the bone Osteitisdeformans Exhibits mosaic pattern or matrix madness Defect in osteoclast There is a rapid osteolytic phase therefore bone is thin

25. Hyperparathyroidism The bone loss predisposes to microfractures and secondary hemorrhages that elicit an influx of macrophages and an ingrowth of reparative fibrous tissue, creating a mass of reactive tissue, known as a brown tumor. The brown color is the result of the vascularity, hemorrhage, and hemosiderin deposition, and it is not uncommon for the lesions to undergo cystic degeneration.

27. Osteonecrosis(Avascular Necrosis) Femoral head with a subchondral, wedge-shaped pale yellow area of osteonecrosis. The space between the overlying articular cartilage and bone is caused by trabecular compression fractures without repair.

30. Pyogenicosteomyelitis, gross The drainage tract in the subperiosteal shell of viable new bone (INVOLUTUM) reveals the inner native cortex (SEQUESTRUM)

32. Pyogenicosteomyelitis, histologic

34. Pyogenicosteomyelitis, x-ray

35. PYOGENIC OSTEOMYELITIS almost always caused by bacteria. Once in bone, the bacteria proliferate and induce an acute inflammatory reaction. The entrapped bone undergoes necrosis within the first 48 hours, and the bacteria and inflammation spread within the shaft of the bone and may percolate throughout the haversian systems to reach the periosteum. Sizable subperiosteal abscesses may form that can track for long distances along the bone surface. Lifting of the periosteum further impairs the blood supply to the affected region, and both the suppurative and the ischemic injury may cause segmental bone necrosis

37. TB Osteomyelitis, gross

39. TB Osteomyelitis, histologic

41. TB Osteomyelitis, x-ray

42. TB Osteomyelitis s/sx: pain on motion, localized tenderness, low-grade fevers, chills, and weight loss. Severe destruction of vertebrae frequently results in permanent compression fractures that produce severe scoliotic or kyphotic deformities and neurologic deficits secondary to spinal cord and nerve compression.

44. Osteosarcoma, gross

46. Osteosarcoma,histologic

48. Osteosarcoma, x-ray

51. Osteosarcoma- Osteoblastic Type LEFT SHOULDER

54. Osteosarcoma Grossly, they are big bulky tumors that are gritty, gray-white, and often contain areas of hemorrhage and cystic degeneration. The tumor cells vary in size and shape and frequently have large hyperchromatic nuclei.

56. Enchondromatosis? Outgrowing of cartilage in the epiphyses of long bones Not a neoplasm Usually left alone unless impinging on nerves of patients

59. Chondrosarcoma, gross With lobules of hyaline and myxoid cartilage permeating throughout the medullary cavity, growing through the cortex and forming a relatively well-circumscribed soft-tissue mass

62. Chondrosarcoma, histologic

64. Chondrosarcoma, x-ray

66. Chondrosarcoma, gross

68. Chondroblastoma Chondroblastoma with scant mineralized matrix surrounding chondroblasts in a chicken wire–like fashion

70. Ewing’s Sarcoma, x-ray

71. Ewing’s Sarcoma Arising in the medullary cavity, Ewing sarcoma usually invades the cortex, periosteum, and soft tissue. The tumor is soft, tan-white, and frequently contains areas of hemorrhage and necrosis. It is composed of sheets of uniform small, round cells They have scant cytoplasm, that is rich in glycogen. There is generally little stroma. Necrosis may be prominent, and there are relatively few mitotic figures in relation to the dense cellularity of the tumor

73. Giant cell tumor, gross

75. Giant cell tumor, histologic

77. Giant cell tumor, x-ray

78. Giant Cell Tumor These are large, red-brown tumors that frequently undergo cystic degeneration. They are mostly composed of uniform oval mononuclear cells that constitute the proliferating component of the tumor. Scattered within this background are numerous osteoclast-type giant cells having 100 or more nuclei that resemble those of the mononuclear cells. Necrosis, hemorrhage, hemosiderin deposition, and reactive bone formation are common secondary features.

80. Osteoarthritis Severe osteoarthritis with small islands of residual articular cartilage next to exposed subchondral bone. 1, Eburnatedarticular surface. 2, Subchondral cyst. 3, Residual articular cartilage.

82. Excised synovium with fronds and nodules typical of pigmented villonodularsynovitis(arrow).

84. ????

86. Nodular Fasciitis A highly cellular lesion composed of plump, randomly oriented spindle cells surrounded by myxoidstroma. Note the prominent mitotic activity

88. Malignant Fibrohistiocytic tumor There are fascicles of plump spindle cells in a swirling (storiform) pattern.

90. Rhabdomyosarcoma, gross

92. Rhabdomyosarcoma, x-ray

99. Rhabdomyosarcoma INTERCAPSULAR MASS

102. Rhabdomyosarcoma, histo

103. The rhabdomyoblasts are large and round and have abundant eosinophilic cytoplasm; no cross-striations are evident here

105. Alveolar rhabdomyosarcoma with numerous spaces lined by tumor cells

106. Rhabdomyosarcoma Alveolar rhabdomyosarcoma with numerous spaces lined by tumor cells Histologically the tumor is traversed by a network of fibrous septae that divide the cells into clusters or aggregates that creates a crude resemblance to pulmonary alveolae. The tumor cells are moderate in size, and many have little cytoplasm. Those in the center of the aggregates are dyscohesive, while those at the periphery adhere to the septae.

107. Peripheral nerve and skeletal muscle

109. Traumatic neuroma Disordered orientation of nerve fiber bundles (purple) intermixed with connective tissue (blue)

111. Duchenne Muscular dystrophy variation in muscle fiber size, increased endomysial connective tissue, and regenerating fibers (blue hue).

113. Nemalinemyopathy Numerous rod-shaped, intracytoplasmic inclusions within muscle fibers (dark purple structures)

115. Mitochondrial myopathy A congenital myopathy Mitochondrial myopathy showing an irregular fiber with subsarcolemmal collections of mitochondria that stain red with the modified Gomoritrichrome stain (ragged red fiber). Red inclusion in the mitochondria or parking lot inclusions