Histopathology - Lymph Node Flashcards
Caseous Necrosis – Lymphadenitis Tuberculosa
Necrosis (~coagulative + granuloma formation) in infected tissue not related to blood supply o Caused by mycobacterium infection
TNF, hypoxia, free radical injury
Amorphous eosinophilic part in the center is the necrotic core with granular debris
Structure disappears, becomes foamy pink “tuberculitic granuloma”
o Granulomas surrounded by histiocytes (=mononuclear phagocytes), lymphocytes and Langerhans giant cells.
o Activated macrophages surround the necrotic core. The ones with pink, granular cytoplasm and indistinct cell boundaries are epitheloid cells because they resemble epithelia.
Fibroblastic layer surrounds the granuloma in an attempt to “wall off” the microbe from healthy tissue. Lymphocytes (T helper cells) here.
Sarcoidosis
“Boeck” sarcoidosis
Granuloma formed
Non-infectious, cause unknown but probably an immune malfunction
Lymph node, lung, and subcutaneous tissue are common sites. Mikulicz syndrome is when
the eyes and lacrimal glands are involved.
Here, the typical structure of the lymph node is lost
High power: dark islands of lymphocytes
No necrosis: sarcoidosis is a non-necrotizing granuloma (unlike tuberculoma)
Langerhans type giant cells
o Contain Schaumann bodies (round laminated concretions of calcium proteins) and asteroid bodies (stellate structures), but these are hard to see here
Most common characteristic is bilateral hilar lymphadenomegaly, in which lymph nodes grow in hilum of lungs. If untreated, will induce lung fibrosis and honeycomb lung.
Lymph Node Metastatic Carcinoma
Large paler purple mass is the neoplasm. More regular lymph node features can be seen at the periphery
o Encapsulated structure within normal lymph tissue
Trabecules are made up of crowded cells
Islands of eosiniphilic material looks like thyroid gland colloid
o Characteristic of papillary thyroid carcinoma which has spread into LN Sinus histiocytes at border are a reactive process
Follicular Hyperplasia – H&E
Capsule is intact
Size of LN is 16,000 micrometers = 16 mm. >5 is pathological.
We should see secondary lymph follicles and paracortical cells.
o There are lymphoid follicles here of variable sizes, some fused
o The marginal zone is not present; we know this is not an abdominal LN
o Follicle germinal center and mantle zone are seen. Germinal center shows normal
asymmetry/polarization
Follicles are site of cell maturation and apoptosis. There are mitotic figures and tingible
histiocytes remove the apoptotic cells.
The cells that are surrounded by lose, white space are the tingible histiocytes.
o Containing phagocytosed, apoptotic cells, i.e. tingible bodies
o “Starry sky” appearance
This is hyperplasia of the follicles, a reactive condition.
Follicular Lymphoma H&E
13 mm
Capsule is broken in parts
Germinal centers more monomorphic compared to follicular hyperplasia
Pathological:
o No polarization of follicles
o No starry sky pattern
Lack of apoptosis means that unhealthy cells can proliferate
Follicular Lymphoma BCL-2 immunohistochemistry
BCL-2+ is in the interfollicular space. Here, it is pathologically expressed in the follicle.
The pathological protein from the Bcl/Ig heavy chain is anti-apoptotic, causing growth
Ki67 is low here compared to normal LN
o Ki67 is a nuclear marker for cell proliferation. This is an indolent, low-grade disease
Hodgkin Lymphoma
Medulla and capsule are fibrotic
No germinal centers
There are 2 cell types:
o Small cells are lymphocytes
o Big cells with lobulated nucleus are lacuna cells In HL, B cells don’t express their usual markers
o There is a special immunophenotype of CD15+, 30+ (missing the normal B cell CD20+, 45+)
Reactive T cells surround the lacuna B cells
Types of Sternberg-Reed cells:
o L & H(lymphocytic and histiocytic)/popcorn cells o Mirror cells
o Lacuna cells
