Mycosis fungoides pathophysiology
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Cutaneous T cell lymphoma Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sowminya Arikapudi, M.B,B.S. [2]
Overview
Cutaneous T cell lymphoma arises from T-cells. On microscopic histopathological analysis, atypical lymphoid cells, polymorphous inflammatory infiltrate in the dermis, and lymphocytes with cerebroid nuclei are characteristic findings of mycosis fungoides.
Pathophysiology
- Cutaneous T cell lymphoma is an unusual expression of T-cells, a part of the immune system
- These T-cells are skin-associated, meaning that they biochemically and biologically are most related to the skin, in a dynamic manner
- Sezary syndrome and Mycosis Fungoides are T-cell lymphomas whose primary manifestation is in the skin
- Mycosis Fungoides is the most common type of 'Cutaneous T cell lymphoma' (CTCL)
- Mycosis fungoides is initially an indolent lymphoma but in its later stages can cause peripheral lymphadenopathy and can finally progress to widespread extracutaneous visceral / internal organ involvement
- "Sézary's cells" are T-cells that have pathological quantities of mucopolysaccharides
- Sézary's disease is sometimes considered a late stage of mycosis fungoides
Gross Pathology
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Plaque of mycosis fungoides
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Mycosis fungoides knee
Microscopic Pathology
- Mycosis fungoides has been divided into three stages:
- Premycotic stage
- Mycotic stage
- Tumorous stage
- The premycotic stage
- Non-diagnostic and represented by chronic nonspecific dermatisis associated with psoriasiform changes in epidermis
- The mycotic stage
- Shows a polymorphous inflammatory infiltrate in the dermis that contains small numbers of frankly atypical lymphoid cells
- These cells may line up individually along the epidermal basal layer
- The latter finding if unaccompanied by spongiosis is highly suggestive of mycosis fungoides
- Tumorous stage
- Dense infiltrate of medium sized lymphocytes with cerebroid nuclei, expands the dermis
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Sézary's disease
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61-year-old man presented in 1972 with unrelenting pruritus of six months’ duration. On the right is his peripheral blood film stained with Periodic Acid-Schiff (PAS) showing a neoplastic T cell (Sézary cell).
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Pleomorphic abnormal T cell with the characteristic cerebriform nuclei (Peripheral blood - MGG stain)
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Features: Nests of lymphocytes in the epidermis; "Pautrier microabscesses". Single lymphocytes in epidermis; "lymphocyte exocytosis". Short linear arrays of lymphocytes along the basal layer of the epidermis; "epidermotropism".
