A 22-year-old otherwise healthy man presented with a year’s history of multiple, asymptomatic, and gradually progressive hypo-pigmented to depigmented patches over the trunk of size varying from 2 to 5 cm [Figure 1]. Some patches showed greying and loss of hair. A single, scaly, atrophic plaque, 3 cm × 5 cm in size, with superimposed reddish-brown papular lesions was noted on the right lateral side of the trunk [Figure 2]. Cutaneous examination failed to demonstrate a decrease or loss of sensation on any patch. No thickening of cutaneous nerves or peripheral nerve trunks was found. General and systemic examination was unremarkable. Routine laboratory parameters such as complete hemogram, thyroid profile, and fasting blood glucose were normal. A punch biopsy was performed, both from a hypo-pigmented patch and the atrophic plaque, and the photomicrograph is shown in Figure 3.
Figure 1.
Multiple, asymptomatic hypo-pigmented patches over the trunk of varying sizes
Figure 2.
A single, scaly atrophic plaque with superimposed reddish-brown papular lesions on the right lateral side of the trunk
Figure 3.
Epidermal atrophy, basal cell layer destruction, presence of halo lymphocytes within the epidermis (epidermotropism), and lymphocyte tagging at dermo-epidermal junction [H and E 400×]
What is your diagnosis?
Answer: Hypo-pigmented Mycosis Fungoides.
Histopathological findings: Slight focal epidermal atrophy with destruction of basal cell layer, tagging of lymphocytes at the dermo-epidermal junction, and lymphocytic infiltration into the epidermis suggestive of epidermotropism was seen. Many of the intra-epidermal lymphocytes showed a halo around them. Marked pigment incontinence was seen. Immunohistochemical staining for CD3, CD4, and CD8 was done, and a predominance of CD8+ve T-cells was demonstrated.
Discussion
The differential diagnoses considered in our case were vitiligo, progressive macular hypo-pigmentation, lichen sclerosus et atrophicus, and BT leprosy. However, the histopathological findings along with the demonstration of CD8+ve lymphocytes on immunohistochemistry proved it to be a case of hypo-pigmented sub-type of mycosis fungoides (MF). For the purpose of staging, a peripheral blood smear along with a complete hemogram was done, which did not show any Sezary cells. Abdominal ultrasound and computerised tomography-thorax did not reveal any lymphadenopathy or other abnormality. Bone marrow aspiration and whole-body positron emission tomography scan were refused by the patient. As the body surface area involvement was less than 10%, no lymphadenopathy was revealed on clinical and radiological examination, and Sezary cells were absent, our patient’s disease was staged as stage 1A, which is usually associated with a good prognosis. The patient was started on NB-UVB therapy with partial response after 2 months but was subsequently lost to follow-up.
Hypo-pigmented MF is a sub-type of cutaneous T-cell lymphoma that presents with hypo-pigmentation and the absence of classic lesions.[1] It commonly occurs in Asian populations or dark-complexioned people. A study of 15 patients from India found it to be more common in the second and fourth decades of life. Lesions were mostly present on the trunk and extremities and were asymptomatic in 80% of patients.[2] The other skin changes were subtle atrophy in 46.66%, scaling in 20%, and focal changes of poikiloderma in 26.66% of patients.[2] The latent period between onset and diagnosis was around 3.83 years, and many cases are misdiagnosed as Hansen’s disease.[2] The disease is said to be more prevalent in females, but certain studies show no sex predilection. Histologically, most cases show characteristic features of MF, but immunohistochemistry has found a predominance of CD8+ve cell infiltrate in the majority of cases.[1] Treatment options depend on the stage of the disease and include phototherapy, topical steroids, topical and systemic chemotherapies, local superficial radiotherapy, the histone deacetylase inhibitor vorinostat, total skin electron radiation, photopheresis, systemic therapies (e.g., retinoids and rexinoids), biological therapies (e.g., interferons), and allogenic bone marrow transplant.[2,3] This sub-type is associated with a better prognosis than other classical forms of MF, and though the lesions are often persistent, they rarely progress to terminal stages.[3,4] The CD8+ve T-lymphocytes might be the main cause for inhibition of melanogenesis. As these cells also suppress the progress of the neoplasm, the hypo-pigmentation may actually act as a good prognostic marker.[3] The differences between the hypo-pigmented and patch stages of classical MF are summarised in Table 1.[5]
Table 1.
Differentiating features between classical MF and hypo-pigmented sub-type of MF
| Features | Classical mycosis fungoides | Hypopigmented mycosis fungoides |
|---|---|---|
| Age group | Elderly (5th–6th decade) | Paediatric age group and young adults |
| Fitzpatrick skin type | Low phototypes (Fair-skinned) | High phototypes (Dark-skinned) |
| Gender | Males | Females or no sex predominance |
| Ethnicity | Caucasian | Asian and African population |
| Types of lymphocytes in immunohistochemistry | Predominantly CD4+ type | Predominantly CD8+ type |
| Epidermotropism | Not intense in the early stages | Intense |
| Pautrier micro-abscess | Present commonly | Seldom found |
| Prognosis | Poor | Excellent |
Hypo-pigmented patches are common skin lesions encountered in clinical practice. Our case shows that MF, though rare, should be considered as a differential diagnosis as early treatment will result in a better prognosis.
Learning points
Hypo-pigmented MF should be considered as a differential in patients presenting with hypo-pigmented to depigmented skin lesions.
Histopathological evaluation is of utmost importance in the diagnosis; hence, should be frequently performed in these patients.
This type of MF has a good prognosis; hence, early detection and treatment are beneficial.
There is a possibility that the true incidence of this variant of MF is underestimated due to a lack of histopathology. Thus, a high index of clinical suspicion must be maintained.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
References
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