Haematology: mycosis fungoides: practice question

A Pathology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pathology · Haematology: mycosis fungoides

Sample item

A 58-year-old man has had scaly patches on the buttocks for years, which have thickened into plaques. A biopsy shows atypical lymphocytes with cerebriform nuclei infiltrating the epidermis and forming Pautrier microabscesses. What is the cell of origin of this neoplasm?

AMature B cellBNatural killer cellCMature CD4-positive helper T cellDCytotoxic CD8-positive T cell

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Mature CD4-positive helper T cell

Mycosis fungoides is a cutaneous T-cell lymphoma of skin-homing CD4-positive helper T cells, which show epidermotropism and form Pautrier microabscesses. It progresses from patch to plaque to tumour stage. Sezary syndrome is the leukaemic form with erythroderma and circulating cerebriform cells.

Option by option

A. Mature B cell
A B-cell origin would give a different histology and not epidermotropism with cerebriform nuclei.
B. Natural killer cell
NK-cell lymphomas involve nose and extranodal sites and are not skin-patch lymphomas of this kind.
C. Mature CD4-positive helper T cell (correct)
The neoplastic cells are CD4-positive helper T cells homing to skin.
D. Cytotoxic CD8-positive T cell
CD8-positive cytotoxic lymphomas are rarer variants and do not define classic disease.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, Mature CD4-positive helper T cell. Mycosis fungoides is a cutaneous T-cell lymphoma of skin-homing CD4-positive helper T cells, which show epidermotropism and form Pautrier microabscesses.

Why is "Mature B cell" not the answer?

A B-cell origin would give a different histology and not epidermotropism with cerebriform nuclei.

Why is "Natural killer cell" not the answer?

NK-cell lymphomas involve nose and extranodal sites and are not skin-patch lymphomas of this kind.

Why is "Cytotoxic CD8-positive T cell" not the answer?

CD8-positive cytotoxic lymphomas are rarer variants and do not define classic disease.

What concept does this question test?

It tests Haematology: mycosis fungoides in Pathology. It progresses from patch to plaque to tumour stage. Sezary syndrome is the leukaemic form with erythroderma and circulating cerebriform cells.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Haematology: mycosis fungoides?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.