Mycosis fungoides pathophysiology

Cutaneous T cell lymphoma Microchapters
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Overview
Classification Mycosis fungoides Sezary syndrome
Pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sowminya Arikapudi, M.B,B.S. [2]

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

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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  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".

References

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