Other MalignanciesAdvanced · 5 min read

Cutaneous Lymphomas (CTCL/MF)

Mycosis fungoides shows orange-yellow structureless areas, fine scale, and the spermatozoa-like (J-shaped) vessels that distinguish early MF from chronic dermatitis on dermoscopy.

By Dr. Yehonatan KaplanPublished Updated

In brief

Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma (CTCL), classically presenting as patches and plaques that mimic chronic dermatitis or psoriasis. Diagnosis is delayed by years in many patients because the histopathological criteria are subtle in early disease. Dermoscopy has emerged as a useful adjunct: the Lallas study comparing early MF to chronic dermatitis identified two reliable discriminators, namely orange-yellow structureless areas and short linear (spermatozoa-like) vessels in MF, contrasting with dotted vessels in dermatitis. These dermoscopic features do not replace biopsy but they help select which patches and plaques to biopsy in patients with chronic eruptions previously labeled as dermatitis. Tumor-stage MF and other CTCL variants (Sezary syndrome, lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma) require histopathology, immunophenotyping, and clonality studies for diagnosis.

Clinical content

01Patch-stage MF presents as scaly erythematous patches in non-sun-exposed sites (buttocks, trunk, breasts, proximal extremities), often labeled as eczema or psoriasis for years before diagnosis. Dermoscopy of early patch MF shows orange-yellow structureless areas, fine surface scaling, and short linear vessels with a characteristic J-shape or spermatozoa-like morphology in approximately half of cases.

02Plaque-stage MF lesions are infiltrated, indurated, and well-demarcated. Dermoscopy reveals more pronounced orange-yellow areas, the linear vessels become more visible, and atrophy or telangiectasia may emerge in poikiloderma vasculare atrophicans (a poikilodermatous variant of MF).

03Tumor-stage MF presents as nodules or tumors arising from preexisting patches/plaques or de novo. Dermoscopy is non-specific at this stage, with milky-red areas, polymorphous vascular patterns including arborizing and dotted vessels, ulceration, and yellow-orange background. The discriminating clinical clue is the appearance of nodules on a background of preexisting MF patches/plaques.

04The spermatozoa-like (J-shaped) vessels are short linear vessels with a curved or hook-shaped end, resembling the head and tail of a spermatozoon. They were detected in approximately 50% of early MF cases in the Lallas series and are not described in chronic dermatitis or psoriasis. Although they are not present in every MF lesion, when seen in a chronic eczematous patch, they strongly suggest MF and warrant biopsy.

05Chronic dermatitis and psoriasis differ dermoscopically. Dermatitis shows dotted vessels in a patchy distribution and yellow scales/crusts. Psoriasis shows dotted vessels in a regular homogeneous distribution and white scales. MF contrasts with both by showing short linear (J-shaped) vessels and orange-yellow structureless areas, lacking the regular dotted vascular pattern.

06Other CTCL variants have different dermoscopic features. Lymphomatoid papulosis (LyP) presents as recurrent crops of papules and small nodules that involute spontaneously over weeks. Dermoscopy shows central whitish structureless areas with peripheral linear or polymorphous vessels and occasional crust. Primary cutaneous anaplastic large cell lymphoma (pcALCL) presents as solitary or grouped nodules with frequent ulceration and is dermoscopically non-specific (polymorphous vessels, ulceration, milky-red areas).

07Folliculotropic MF is a poor-prognosis variant that involves hair follicles with comedo-like papules, alopecia, and acneiform lesions. Dermoscopy shows perifollicular accentuation, follicular plugs, and broken or dystrophic hairs. The head and neck distribution and association with scalp alopecia distinguish it from typical MF.

08The dermoscopic role in MF is to flag suspect patches and plaques for biopsy in patients with chronic eruptions previously diagnosed as eczema or psoriasis. Dermoscopy does not establish the diagnosis; histopathology with T-cell receptor clonality, immunophenotyping (CD2, CD3, CD4, CD7, CD8, CD30), and clinicopathologic correlation by an experienced cutaneous lymphoma center is required.

Key dermoscopic features

Orange-yellow structureless areas
Diffuse or patchy orange-yellow discoloration. Common in early MF and a key discriminator from dotted-vessel pattern of dermatitis or psoriasis.Early MF
Spermatozoa-like (J-shaped) short linear vessels
Short linear vessels with a curved hook end, resembling spermatozoa. Detected in approximately 50% of early MF cases in the Lallas series. Not described in dermatitis or psoriasis.Early MF (highly specific)
Fine surface scale
Often white to yellowish, in patchy distribution. Less prominent than psoriasis scaling.Patch-stage MF
Telangiectasia and poikiloderma
Telangiectatic vessels, atrophy, and pigmentation in poikiloderma vasculare atrophicans. A specific MF variant.Poikilodermatous MF
Perifollicular accentuation and follicular plugs
Hair follicle involvement with comedo-like papules and alopecia.Folliculotropic MF
Milky-red areas with polymorphous vessels
Tumor-stage MF or pcALCL. Non-specific; histopathology required.Tumor-stage MF / pcALCL
Central whitish structureless area + peripheral vessels
Lymphomatoid papulosis pattern. Self-resolving papules with central depression.Lymphomatoid papulosis
Dotted vessels in regular distribution (psoriasis pattern)
Discriminator FROM MF. Regular dotted vessels with white scales = psoriasis, not MF.Psoriasis (NOT MF)
Dotted vessels in patchy distribution (dermatitis pattern)
Discriminator FROM MF. Patchy dotted vessels with yellow scales = dermatitis, not MF.Chronic dermatitis (NOT MF)
Ulceration
Tumor-stage MF, pcALCL, or transformed MF. Non-specific; biopsy required.Advanced MF / pcALCL

High yield clinical points10 pearls in 4 groups

Recognition & pattern analysis

5 points
50%
Spermatozoa-like vessels are highly specific for MF. Short linear vessels with a curved hook end (J-shape, like spermatozoa) are detected in ~50% of early MF and are not seen in chronic dermatitis or psoriasis.
2
Dotted vessels = NOT MF. Regular dotted vessels with white scales = psoriasis. Patchy dotted vessels with yellow scales = dermatitis. Linear vessels with orange-yellow areas = MF. The vascular morphology is the most reliable discriminator.
3
Distribution favors MF: bathing trunk pattern. MF classically involves non-sun-exposed sites (buttocks, lower trunk, breasts, proximal extremities). Eczema or psoriasis involving these sites in an asymmetric distribution should raise suspicion.
4
Folliculotropic MF: head and neck plus alopecia. Comedo-like papules, alopecia, and acneiform lesions on the head and neck are folliculotropic MF until proven otherwise. This variant has worse prognosis.
5
Sezary syndrome = leukemic CTCL with erythroderma. Erythroderma plus lymphadenopathy plus circulating malignant T cells (Sezary cells) = Sezary syndrome. Refer urgently to a CTCL specialist. Dermoscopy is non-specific in erythroderma.

Pitfalls & mimics

1 point
10-20%
Lymphomatoid papulosis is paradoxical. Recurrent crops of papules that resolve spontaneously over weeks but is a CD30+ lymphoproliferative disorder with 10-20% lifetime risk of secondary lymphoma. Biopsy is mandatory; do not dismiss as benign because it self-resolves.

When to biopsy

3 points
1
Orange-yellow + linear vessels = think MF. In a patient with a chronic eczematous or psoriasiform eruption, orange-yellow structureless areas plus short linear (J-shaped) vessels suggest MF. Biopsy is warranted.
2
Sequential biopsies are often needed. Early MF can be histologically subtle. If clinical suspicion remains high after a non-diagnostic biopsy, repeat biopsy from a different site at a later time. Dermoscopy can help target the most suspect patch.
3
Topical steroid use can mask MF dermoscopy. Long-term topical steroid use suppresses the inflammatory infiltrate and may transiently obscure dermoscopic features. Stop steroids 2-4 weeks before biopsy when feasible.

Recent changes (2022 onward)

1 point
1
MF management is staged and complex. Patch/plaque MF (stage IA-IB) is treated with topical steroids, NB-UVB, PUVA, topical chlormethine (mechlorethamine) gel, or topical bexarotene; low-dose total skin electron beam therapy and topical imiquimod are options in selected cases. Tumor-stage MF requires radiotherapy, retinoids, interferon, brentuximab vedotin (CD30+), mogamulizumab (CCR4), or denileukin diftitox-cxdl (Lymphir; FDA 2024 for relapsed/refractory CTCL). Refer to a cutaneous lymphoma center.

Lectures covering this topic1 lecture

Academy 2025ACAD25 · #12
Rare Skin Tumors
Giuseppe Argenziano

Notable updates & conceptual milestones4 updates

Spermatozoa-like vessels described in early MF

2013

Lallas et al. described the short linear J-shaped vessels in 2013, providing a dermoscopic discriminator between early MF and chronic dermatitis that has since been replicated.

Mogamulizumab for relapsed/refractory MF and Sezary

2018

Anti-CCR4 monoclonal antibody mogamulizumab gained FDA approval in 2018 for relapsed or refractory MF and Sezary syndrome, with significantly improved progression-free survival vs vorinostat in the MAVORIC trial.

Brentuximab vedotin for CD30+ CTCL

2017

Antibody-drug conjugate brentuximab vedotin (anti-CD30 with monomethyl auristatin E) is approved for CD30+ MF and primary cutaneous anaplastic large cell lymphoma based on the ALCANZA trial.

Total skin electron beam therapy (TSEBT)

2015

Low-dose TSEBT (12 Gy) achieves response rates comparable to standard-dose TSEBT (36 Gy) with less toxicity, allowing repeat courses for relapsed disease.

Bottom line

Mycosis fungoides shows orange-yellow structureless areas, fine scale, and the spermatozoa-like (J-shaped) vessels that distinguish early MF from chronic dermatitis on dermoscopy.

10 clinical points · 4 recent updates · 6 references

References

Sources cited in the lecture content or that underpin the clinical points above. Verify with primary sources before practice changes.

  1. [1]
    Lallas A, Apalla Z, Lefaki I, et al. Dermoscopy of early stage mycosis fungoides. J Eur Acad Dermatol Venereol. 2013;27(5):617-621.
    PubMed: 22404051DOI: 10.1111/j.1468-3083.2012.04499.x· Original study comparing early MF and chronic dermatitis dermoscopically. Identifies orange-yellow areas and spermatozoa-like (short linear J-shaped) vessels as discriminators of MF.
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    Bombonato C, Pampena R, Lallas A, Giovanni P, Longo C. Dermoscopy of Lymphomas and Pseudolymphomas. Dermatol Clin. 2018;36(4):377-388.
    PubMed: 30201147DOI: 10.1016/j.det.2018.05.005· Comprehensive review of dermoscopic features across CTCL variants including MF, lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma, and pseudolymphomas.
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    Errichetti E, Stinco G. The Practical Usefulness of Dermoscopy in General Dermatology. G Ital Dermatol Venereol. 2015;150(5):533-546.
    PubMed: 26086412· Reviews dermoscopic features of inflammatory and neoplastic conditions including MF, with emphasis on the differential diagnosis from dermatitis and psoriasis.
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    PubMed: 30635287DOI: 10.1182/blood-2018-11-881268· Current WHO-EORTC classification of primary cutaneous lymphomas including MF, Sezary syndrome, lymphomatoid papulosis, and primary cutaneous CD30+ lymphoproliferative disorders.
  5. [5]
    Kim YH, Bagot M, Pinter-Brown L, et al. Mogamulizumab versus vorinostat in previously treated cutaneous T-cell lymphoma (MAVORIC): an international, open-label, randomised, controlled phase 3 trial. Lancet Oncol. 2018;19(9):1192-1204.
    PubMed: 30100375DOI: 10.1016/S1470-2045(18)30379-6· Pivotal MAVORIC trial establishing mogamulizumab as an effective therapy for relapsed/refractory MF and Sezary syndrome.
  6. [6]
    Prince HM, Kim YH, Horwitz SM, et al. Brentuximab vedotin or physician's choice in CD30-positive cutaneous T-cell lymphoma (ALCANZA): an international, open-label, randomised, phase 3, multicentre trial. Lancet. 2017;390(10094):555-566.
    PubMed: 28600132DOI: 10.1016/S0140-6736(17)31266-7· ALCANZA trial establishing brentuximab vedotin as superior to standard treatment for CD30+ CTCL, including MF and primary cutaneous anaplastic large cell lymphoma.