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PubMed This is a summary of 16 peer-reviewed journal articles Updated
Dermatology

The Long Road to Diagnosis: Symptoms and Mimics of PCL

At a Glance

Primary cutaneous lymphoma (PCL) is a slow-growing skin cancer often misdiagnosed as eczema or psoriasis because early lesions look identical to benign skin inflammation. It takes an average of 3 to 4 years to confirm a diagnosis as the disease slowly progresses from flat patches to raised plaques.

It is common for patients with primary cutaneous lymphoma (PCL) to feel frustrated or even angry when they reflect on the years leading up to their diagnosis. For most, this journey involves a series of doctors and a list of different diagnoses—usually eczema, psoriasis, or a drug eruption (a skin reaction to medication) [1][2].

This diagnostic delay is not typically due to medical error; it is a result of how PCL (specifically the most common type, Mycosis Fungoides) behaves in its early stages.

Why PCL is the “Great Mimicker”

In the beginning, PCL is a “great mimicker” because the malignant cells move into the skin in a way that looks identical to benign inflammation [3].

  • Visual Similarity: The early lesions—called patches—are flat, red, and scaly. They look exactly like chronic eczema or psoriasis [2][4].
  • Location Clues: One hint that it might be PCL rather than a common skin condition is the “bathing suit distribution.” While psoriasis often appears on elbows and knees, PCL frequently shows up in areas protected from the sun, such as the hips, buttocks, and underarms [5].
  • Unresponsiveness: A major “red flag” is a skin condition that simply does not get better with standard treatments, like high-potency steroid creams, or that returns immediately after treatment stops [6].

The Typical Progression of Symptoms

For many patients, the disease moves through three distinct phases. This progression is often very slow, taking years or even decades to move from one phase to the next [3].

  1. Patch Stage: Flat, scaly, and often itchy areas of skin. This is the stage most commonly confused with eczema [2].
  2. Plaque Stage: The lesions become thickened, raised, and feel “leathery” to the touch [3].
  3. Tumor Stage: Raised, solid nodules or bumps develop. These can sometimes break open or “ulcerate” [3][7].

The Danger of “Masking” with Biologics

In recent years, doctors have used powerful biologics (like dupilumab for eczema or TNF-inhibitors for psoriasis) to treat severe skin disease. While these are life-changing for patients with true eczema or psoriasis, they can be problematic if the underlying cause is actually an undiagnosed lymphoma [8].

Research suggests that these medications can “unmask” or potentially accelerate the progression of PCL [9][10]. Because these drugs suppress specific parts of the immune system, they may inadvertently take the “brakes” off the lymphoma cells, causing the skin lesions to worsen or spread more rapidly [9][11]. If you were on a biologic and your skin suddenly got worse, it was likely the drug allowing the occult (hidden) lymphoma to become more visible [12].

Validating the “Diagnostic Odyssey”

The average time from the first spot appearing to a confirmed diagnosis is 36 to 51 months (3 to 4.25 years) [13][14]. It is helpful to view this time not as a “lost” period, but as the time it took for the disease to develop enough characteristic features for a biopsy to finally confirm it. Because early PCL lacks specific markers, it often takes several biopsies over several years before a dermatopathologist (a skin-tissue expert) can see the malignant pattern clearly [15][16].

Return to Home

Common questions in this guide

Why is primary cutaneous lymphoma often misdiagnosed as eczema?
Early PCL lesions are flat, red, and scaly, looking identical to benign inflammation like eczema or psoriasis. Because the disease lacks specific markers early on, it can take several biopsies over several years for a dermatopathologist to see the malignant pattern.
What are the stages of primary cutaneous lymphoma?
PCL typically progresses slowly through three distinct phases. It begins in the patch stage with flat, scaly skin, moves to the plaque stage where lesions become thickened and leathery, and can advance to the tumor stage with solid nodules that may ulcerate.
Can taking biologics for severe eczema or psoriasis make PCL worse?
Yes, taking immunosuppressive biologics for a misdiagnosed skin condition can inadvertently accelerate underlying lymphoma. Because these drugs suppress parts of the immune system, they may take the brakes off the lymphoma cells and cause lesions to worsen rapidly.
How can I tell the difference between PCL and common skin conditions?
While common skin conditions like psoriasis often appear on exposed areas like elbows and knees, PCL frequently shows up in sun-protected areas like the hips, buttocks, and underarms. A major warning sign is a skin condition that does not improve with standard steroid creams.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Given my history of being treated for eczema/psoriasis, how can we be sure this is primary cutaneous lymphoma and not an inflammatory condition?
  2. 2.Did my previous use of biologics or immunosuppressants potentially mask the lymphoma symptoms or impact the staging?
  3. 3.Should we perform a 'washout' period from my previous treatments before starting a new PCL-directed therapy?
  4. 4.What specific 'red flags' should I watch for on my skin that would signal my disease is moving from the patch stage to the plaque or tumor stage?
  5. 5.Can we review my pathology report to see if there was evidence of T-cell receptor (TCR) clonality or loss of pan-T-cell markers?

Questions For You

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References

References (16)
  1. 1

    Epidemiological changes in cutaneous lymphomas: an analysis of 8593 patients from the French Cutaneous Lymphoma Registry.

    Dobos G, de Masson A, Ram-Wolff C, et al.

    The British journal of dermatology 2021; (184(6)):1059-1067 doi:10.1111/bjd.19644.

    PMID: 33131055
  2. 2

    Fatal mycosis fungoides, misdiagnosed as contact dermatitis.

    Shadmani G, Dumrongkulraksa J, Jahromi AH

    EJNMMI reports 2025; (9(1)):15 doi:10.1186/s41824-025-00249-5.

    PMID: 40307495
  3. 3

    Mycosis fungoides: a review.

    Sheern C, Levell NJ, Craig PJ, et al.

    Clinical and experimental dermatology 2025; (50(12)):2365-2375 doi:10.1093/ced/llaf341.

    PMID: 40721285
  4. 4

    Long-standing dermatitis treated with dupilumab with subsequent progression to cutaneous T-cell lymphoma.

    Hollins LC, Wirth P, Fulchiero GJ, Foulke GT

    Cutis 2020; (106(2)):E8-E11 doi:10.12788/cutis.0074.

    PMID: 32941565
  5. 5

    Safety and Danger Considerations of Novel Treatments for Atopic Dermatitis in Context of Primary Cutaneous Lymphomas.

    Kołkowski K, Trzeciak M, Sokołowska-Wojdyło M

    International journal of molecular sciences 2021; (22(24)) doi:10.3390/ijms222413388.

    PMID: 34948183
  6. 6

    A clinician's guide to cutaneous T-cell lymphoma presenting as recalcitrant eczematous dermatitis in adults.

    Semaan S, Abel MK, Raffi J, Murase JE

    International journal of women's dermatology 2021; (7(4)):422-427 doi:10.1016/j.ijwd.2021.04.004.

    PMID: 34621954
  7. 7

    Characteristics associated with significantly worse quality of life in mycosis fungoides/Sézary syndrome from the Prospective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) study.

    Molloy K, Jonak C, Woei-A-Jin FJSH, et al.

    The British journal of dermatology 2020; (182(3)):770-779 doi:10.1111/bjd.18089.

    PMID: 31049926
  8. 8

    What's New in Cutaneous T-Cell Lymphoma-Associated Pruritus.

    Biazus Soares G, Guitart J, Yosipovitch G

    American journal of clinical dermatology 2024; (25(1)):67-77 doi:10.1007/s40257-023-00823-2.

    PMID: 37971624
  9. 9

    Acceleration of cutaneous T-cell lymphoma following dupilumab administration.

    Russomanno K, Carver DeKlotz CM

    JAAD case reports 2021; (8()):83-85 doi:10.1016/j.jdcr.2020.12.010.

    PMID: 33532533
  10. 10

    Integrative epidemiology and immunotranscriptomics uncover a risk and potential mechanism for cutaneous lymphoma unmasking or progression with dupilumab therapy.

    Cabrera-Perez JS, Carey VJ, Odejide OO, et al.

    The Journal of allergy and clinical immunology 2025; (155(5)):1584-1594 doi:10.1016/j.jaci.2024.10.028.

    PMID: 39521279
  11. 11

    Tumors in the setting of dupilumab use: A review of the literature.

    Guo S, Wang L, Bu D, Liu F

    The World Allergy Organization journal 2025; (18(1)):101006 doi:10.1016/j.waojou.2024.101006.

    PMID: 39758935
  12. 12

    Evolution of Dupilumab-Associated Cutaneous Atypical Lymphoid Infiltrates.

    Sokumbi O, Shamim H, Davis MDP, et al.

    The American Journal of dermatopathology 2021; (43(10)):714-720 doi:10.1097/DAD.0000000000001875.

    PMID: 34132660
  13. 13

    The PROCLIPI international registry of early-stage mycosis fungoides identifies substantial diagnostic delay in most patients.

    Scarisbrick JJ, Quaglino P, Prince HM, et al.

    The British journal of dermatology 2019; (181(2)):350-357 doi:10.1111/bjd.17258.

    PMID: 30267549
  14. 14

    Clinical and epidemiological profile of patients with early stage mycosis fungoides.

    Amorim GM, Niemeyer-Corbellini JP, Quintella DC, et al.

    Anais brasileiros de dermatologia 2018; (93(4)):546-552 doi:10.1590/abd1806-4841.20187106.

    PMID: 30066762
  15. 15

    Phenotypic Variation in Different Lesions of Mycosis Fungoides Biopsied Within a Short Period of Time From the Same Patient.

    Kash N, Massone C, Fink-Puches R, Cerroni L

    The American Journal of dermatopathology 2016; (38(7)):541-5 doi:10.1097/DAD.0000000000000493.

    PMID: 26885605
  16. 16

    Interleukin-12 immunohistochemistry as a diagnostic tool for patch-stage mycosis fungoides.

    Lemchak DM, Akilov OE

    Journal of the American Academy of Dermatology 2016; (75(5)):1053-1054 doi:10.1016/j.jaad.2016.06.019.

    PMID: 27745630

This page is for informational purposes only and does not replace professional medical advice. Always consult your dermatologist or oncologist regarding your symptoms, diagnosis, and treatment plan.

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