07 January 2025
: Case report 
Pediatric Mycosis Fungoides Mimicking Benign Dermatoses: A Report of a Rare Case
Challenging differential diagnosis, Rare disease
Salwa Rosli1EF, Haizlene Abd Halim12E*, Mazapuspavina Md-Yasin12E, Nur Aini Abu Bakar3EDOI: 10.12659/AJCR.945897
Am J Case Rep 2025; 26:e945897
Table 2. Histopathological examination and immunohistochemistry features of mycosis fungoides.
| Cell marker | IHC features of MF | HPE result (2022) | HPE result (2023) | Comments |
|---|---|---|---|---|
| 1) CD3 | Positive in neoplastic T cell.Pan-T cell marker | Positive expression CD3 | The atypical lymphocytes are CD3+ | Positive |
| 2) CD4 | Typical +ve indicating predominant CD4+ helper T cell | Reduced expression of CD4 | CD4 equivocal | Weakly positive |
| 3) CD8 | Usually negative or less expressed compared to CD4, though CD8+ variant exist | Reduced/loss expression of CD8 | Not commented | Positive |
| 1) CD2 & CD5 | Typically positive, as these are pan-T cells markers | Positive CD2 and CD5 expression | Slightly reduced expression of CD2 and CD5 | Positive |
| 2) CD7 | Often negative or reduce expression.Loss of CD7 is a common finding in MF. Help in distinguishing reactive T cell infiltrates | Reduced/loss CD7 expression | Slightly reduced expression of CD7 | Positive |
| 2) T cell receptor (TCR markers) TCR-beta & TCR-gamma | Clonality of T cell receptor, genes can be demonstrated, which support the diagnosis of T cell lymphoma | Not commented | Not commented | Not done |
| 1) CD30 | Usually negative in early MF. But may expressed in transformed large cell variants | Not commented | Not commented | Not done |
| 2) Ki-67(MIB-1) | Proliferation marker that shows increase activity in MF especially in more advance stages | Not commented | Not commented | Not done |
| Other markers | ||||
| 1) CD20 | Negative which help to ruled out B cell lymphomas | Not commented | Not commented | Not done |
| 2) CD56 & CD57 | Typically negative, as these are markers for natural killer (NK-cells) and some T cell lymphomas other than MF | Not commented | Not commented | Not done |
| 1) Epidermotropism | Present of neoplastic T cell within the epidermis | The epidermis shows hyperkeratosis and parakeratosis.Melanocytes are present at base | The epidermis shows few scattered mildly atypical lymphocytes exocytosis exhibiting mildly enlarged irregular nuclear membrane and perinuclear halos | Positive |
| 2) Pautrier’s micro abscesses | Collection of atypical lymphocytes within the epidermis | Not commented | No obvious lymphocytes abscess or basal vacuolar seen | Negative |
| 3) Lymphocytic infiltrate | Atypical T cell in the dermis which often found in a band like pattern | Focal clusters of lymphocytes exocytosis are seen exhibiting irregular nuclear membrane and perinuclear halos. Mitotic activity is noted. Mitotic activity is noted | Not commented | Positive |
| Final interpretation | Suggest early MF.Repeat biopsy if clinically indicated | Mild focal atypical lymphocytes exocytosis.There are more atypical cells than seen on previous biopsy slides, with more convincing reduced expression of the T-lymphocytes markers as compared to current biopsy | ||
| IHC – immunohistochemistry; MF – mycosis fungoides; HPE – histopathological examination. The combination of HPE and IHC is essential for the accurate diagnosis of the MF. | ||||