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Dermoscopy: an easy, noninvasive tool for distinguishing mycosis fungoides from other inflammatory mimics

Saleh, Marwah A.; Abdel Halim, Dalia M.

Journal of the Egyptian Women's Dermatologic Society: September 2014 - Volume 11 - Issue 3 - p 215–219
doi: 10.1097/01.EWX.0000440870.35969.e4
Original articles
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Background Mycosis fungoides (MF), the most common type of cutaneous T-cell lymphoma, can sometimes be indistinguishable from plaque psoriasis (PP), chronic dermatitis, and lichen planus (LP).

Objective The aim of the study was to assess the value of dermoscopy as a quick screening tool to distinguish MF from PP, chronic dermatitis, and LP.

Patients and methods The dermoscopic profiles of 21 MF, 20 PP, 20 chronic dermatitis, and 20 LP patients were included in this study.

Results All 20 PP patients (100%) showed homogenous red globules on a red background with white scales. All 20 LP patients (100%) showed whitish projections. In chronic dermatitis, all 20 (100%) patients showed patchy red dots and globules with yellowish scales. All MF patients showed pinkish homogeneous backgrounds. Whitish scales were seen in 15/21 (71.4%) MF patients. In recent-onset MF (disease duration ≤2months), fine short linear vessels were seen in 4/21 (19%) patients and spermatozoa-like vessels in 3/21 (14.2%) patients. These features were statistically significant when compared with all the 81 examined patients (P=0.0036 and 0.0156, respectively). In contrast, in hyperpigmented MF lesions, dark globules were seen in 10/21 (47.6%) and light brown multifocal pigmentation was seen in 10/21 (47.6%) patients. These features were statistically significant when compared with all the 81 examined patients (P<0.0001).

Conclusion Fine short linear vessels, spermatozoa-like vessels, dark globules, and light brown multifocal pigmentation on a pink homogenous background are highly suggestive of MF. Dermoscopy proved to be a useful tool in distinguishing between MF, PP, chronic dermatitis, and LP.

Department of Dermatology, Faculty of Medicine, Cairo University, Cairo, Egypt

Correspondence to Marwah A. Saleh, MD, Department of Dermatology, Faculty of Medicine, Cairo University, 12411 Cairo, Egypt Tel: +20 122 313 2773; e-mail: salehmarwah@kasralainy.edu.eg

Received September 17, 2013

Accepted November 24, 2013

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Introduction

Mycosis fungoides (MF) is recognized as the most common type of cutaneous T-cell lymphoma (CTCL). Early diagnosis of CTCL remains of crucial interest in clinical practice 1. In early stages, clinical and histopathological diagnosis of MF is difficult and may be indistinguishable from inflammatory dermatoses 2. Malignant T cells in early-stage CTCL are confined to the skin and are difficult to isolate and discriminate from benign reactive cells. T cells from CTCL skin lesions contain a population of large, highly scattered, activated, skin-homing T cells not observed in other inflammatory skin diseases 3. Lallas et al.4 reported that there are specific dermoscopic findings for early MF cases.

Classic MF is erythematous in skin types I, II, and III. In contrast, a hyperpigmented variant of MF is present in individuals with skin type grade higher than III 5. It is characterized pathologically by variable degrees of melanin incontinence.

A dermoscope is a noninvasive tool that detects vascular and morphological structures as well as color variation; therefore, it is widely used in diagnosing inflammatory skin lesions 6–8. Plaque psoriasis (PP) and lichen planus (LP) are among the common papulosquamous dermatoses that exhibit characteristic dermoscopic findings 7,9–12. Moreover, PP, LP, and chronic dermatitis can be indistinguishable from MF.

In this work we sought to determine the effectiveness of dermoscopy in differentiating between MF, PP, chronic dermatitis, and LP.

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Patients and methods

The first 20 PP, 20 early-stage classic MF (≤stage IIa), one poikilodermatous MF, 20 chronic dermatitis, and 20 classic cutaneous LP patients who visited the Dermatology Outpatient Clinic, Kasr Al-Aini, Cairo University, who had not undergone any previous treatment for their condition were enrolled in this study. The patients were subjected to full history taking and clinical examination. A skin biopsy was taken from each patient to confirm the diagnosis. Immunostaining was carried out for MF patients. Dermoscopic images were captured using a digital dermoscopy system derma9500S with a polarization filter (Derma Medical Inc., Yokohama, Japan). All participants were informed according to the Helsinki Declaration of biomedical ethics 13; verbal consent was obtained after proper orientation of the participants with respect to the objectives of the study. Data confidentiality and the impact of the study were respected and maintained.

Selection of the dermoscopic variables included in the evaluation process was based on the available literature data 14. Variables included in the dermoscopic evaluation were the following: (i) dotted vessels; (ii) globular vessels; (iii) fine short linear vessels; (iv) spermatozoa-like structures; (v) orange-yellow patchy areas; (vi) white scales; and (vii) yellow scales.

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Statistical analysis

Data were statistically described in terms of mean±SD, as median and range for continuous quantitative data, and as frequencies (number of cases) and percentages for categorial data. Comparison of continuous quantitative variables between the study groups was made using the one-way analysis of variance test with post-hoc multiple two-group comparisons. For comparing categorical data, the χ2-test was performed. The exact test was used instead when the expected frequency was less than 5. P values less than 0.05 were considered statistically significant. All statistical calculations were carried out using the computer program statistical package for the social science (SPSS Inc., Chicago, Illinois, USA) version 15 for Microsoft Windows.

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Results

A total of 61 patients were examined with a dermoscope: 20 generalized classic plaque MF patients, one poikilodermatous MF patient, 20 generalized PP patients, 20 chronic dermatitis patients, and 20 generalized classic cutaneous LP patients. The patients’ data are listed in Table 1.

Table 1

Table 1

Of 21 MF patients, four (skin type III) had erythematous lesions (disease duration ≤2 months) and 17 (skin type IV) had hyperpigmented lesions. The disease duration ranged from 3 weeks to 3 years. The mean disease duration was 1.6±1.1 years. All the MF patients showed pinkish homogeneous backgrounds (Fig. 1a). Whitish scales were seen in 15/21 (71.4%) patients, dark globules were seen in 10/21 (47.6%) patients, and light brown multifocal pigmentation was seen in 10/21 (47.6%) patients. These features were found to be statistically significant when compared with PP, LP, and chronic dermatitis patients (P<0.0001). In contrast, blue gray globules were seen in 2/21 (10%) patients (Fig. 1b) and patchy red dots and globules were seen in 2/21 (10%) patients (Fig. 1c). These features were not statistically significant when compared with PP, LP, and chronic dermatitis patients. In recent-onset MF, fine short linear vessels were seen in 4/21 (19%) patients (Fig. 1d) and spermatozoa-like vessels were seen in 3/21 (14.2%) patients (P=0.0036 and 0.0156, respectively). These features were statistically significant when compared with PP, LP, and chronic dermatitis patients. One patient had poikilodermatous MF and dermoscopy showed prominent arborizing blood vessels (Fig. 2).

Figure 1

Figure 1

Figure 2

Figure 2

All the PP patients (20/20, 100%) showed homogenous uniform red globules on a red background with white scales (Fig. 1e). On comparing these findings in all the examined patients, these findings were found to be highly specific for PP (P<0.0001).

All the chronic dermatitis patients (20/20, 100%) showed yellowish scales and red dots and globules (P<0.0001) (Fig. 1f and g). Eighteen patients had reddish homogenous backgrounds (P<0.0001), whereas two patients had pinkish homogenous backgrounds (P=0.01).

In LP, the disease duration ranged from 6 months to 3 years. All the LP patients (20/20, 100%) showed pinkish homogenous backgrounds with projections of whitish structures of various sizes that corresponded to Wickham striae (Fig. 1h). On comparing these findings in all the examined patients, these findings were found to be highly specific for LP (P<0.0001). Table 2 summarizes the dermoscopic findings of all the patients.

Table 2

Table 2

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Discussion

Dermoscopy is a noninvasive practical tool that can aid naked-eye clinical examination in diagnosing several skin diseases. MF is a simulator of many diseases 15. It can present with psoriasiform 16 or LP-like lesions. In this work we sought to evaluate the use of a dermoscope in distinguishing between MF, PP, chronic dermatitis, and LP. Our results suggest significant dermoscopic features distinguishing MF, PP, chronic dermatitis, and LP that can assist the clinical diagnosis of these conditions.

Our results showed that fine short linear vessels and spermatozoa-like blood vessels are highly suggestive of early-stage erythematous MF, which agreed with the results of Lallas et al.4. Moreover, our results showed that light brown multifocal pigmentation and dark globules on a pink homogenous background are highly suggestive of hyperpigmented MF. These features have not been described before. One observation that could be of interest is that the vascular structures were seen more often in recent-onset MF (disease duration ≤2 months) and skin type III, whereas the pigmentary lesions were in older MF lesions and skin type IV patients.

The combined use of dermoscopy and conventional histopathology means that skin tumors can now be analyzed using separate yet complementary methods. Histologic sections, for example, provide a vertical view of lesions, whereas dermoscopic images provide a horizontal view of the entire lesion. This is why it is somewhat difficult to correlate dermoscopic and histopathologic findings with precision. Nonetheless, the complementary horizontal perspective offered by dermoscopy is a valuable addition to the findings offered by conventional histology 17.

Several studies 18–20 have reported correlations between dermoscopic and histopathologic findings mainly for pigmented skin lesions. No attempts were made to find a correlation between dermoscopic and histopathologic findings in MF. In our work a pinkish homogeneous background may correspond to dilatation of dermal vessels, whitish scaly areas may correspond to parakeratosis, light brown multifocal pigmentation may correspond to basal melanosis, dark brown globules may correspond to epidermal or horny layer melanin or blood, and blue-gray globules may correspond to melanophages in the papillary dermis. The presence of melanophages in the papillary dermis was consistent with the findings of Pavlovsky et al.5 who found similar changes in a hyperpigmented variant of MF.

Poikilodermatous MF is a rare variant of MF 21. It is characterized by atrophic telangiectatic plaques with reticulate pigmentation. Breast is one of the common sites for poikilodermatous MF. Our patient had poikilodermatous MF in her breasts (Fig. 2). The dermoscopic features were arborizing blood vessels, which reflect the dilated blood vessels in the dermis 22.

Moreover, our results showed that PP patients showed characteristic homogenous red globules on a reddish background and whitish scales, which agreed with the results of many research groups 6,7. Interestingly, these features were absent in MF, chronic dermatitis, and LP patients.

In contrast, a reddish homogenous background with patchy red dots and globules in the presence of yellowish scales is highly suggestive of chronic dermatitis. This agrees with the results of previous studies 9.

Moreover, the presence of whitish projections was found only in LP. However, we did not detect red lines or red dots in our LP patients as reported in some studies 7. One explanation could be that cutaneous LP may resolve spontaneously and these lesions might be subsiding and therefore may have lost their vascular element.

The limitation of this work is that we had only one poikilodermatous MF patient and therefore we could not compare the dermoscopic features between classic and poikilodermatous MF. Moreover, it would be interesting to compare the dermoscopic features between classic MF and other clinicopathological variants.

Finally, we can conclude that fine short linear vessels, spermatozoa-like vessels, dark globules, and light brown multifocal pigmentation on a pink homogenous background are highly suggestive of MF. Although the dermoscope proved to be useful in distinguishing early-stage MF from other inflammatory mimics, further large-scale studies are needed to confirm the specificity of the current study on dermoscopic features of MF in our Egyptian skin type.

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Acknowledgements

The authors are grateful to Dr Masaru Tanaka (Tokyo Women’s Medical University, Japan) for his valuable discussion.

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Conflicts of interest

There are no conflicts of interest.

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Keywords:

chronic dermatitis; dermoscopy; lichen planus; mycosis fungoides; psoriasis

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