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MF variantCTCLICD-10 C84.4

Granulomatous slack skin

GSS · pendulous granulomatous mycosis fungoides · cutis pendula

Granulomatous slack skin (GSS) is a rare WHO-recognised subtype of mycosis fungoides characterised by progressive pendulous, lax skin lesions in major flexures (axillae, groin), with granulomatous infiltrates and elastolysis on histology. It usually has an indolent course but carries an association with second haematological malignancies (Hodgkin lymphoma, MF transformation). Recognition matters because clinical impression alone may be missed; biopsy is essential.

CurrentLast reviewed 16 May 2026

Pathogenesis

  • Clonal T-cell infiltrate with granulomatous reaction; T cells produce elastolytic enzymes degrading dermal elastic fibres.
  • Most cases CD4+ phenotype; clonal T-cell receptor rearrangement.
  • WHO-HAEM5 classifies as a variant of mycosis fungoides.
  • Onset typically 3rd-4th decade; slight male predominance.

Clinical features

  • Slowly progressive over years; initially erythematous patches and plaques.
  • Evolves to pendulous, atrophic, hyperpigmented lax skin folds in axillae, groin, antecubital fossae.
  • Indolent course; rarely systemic dissemination.
  • Association with second haematological malignancy:
    • Hodgkin lymphoma (~30%).
    • Classic MF / Sézary syndrome.
    • Non-Hodgkin lymphoma.
  • Asymptomatic; cosmetic and functional issues (skin chafing).

Investigations

  • Skin biopsy: dense dermal granulomatous infiltrate with atypical T cells and multinucleated giant cells engulfing elastic fibres (elastophagocytosis); marked elastolysis.
  • IHC: CD3+, CD4+ predominant; CD8+ scattered; loss of CD7.
  • TCR gene rearrangement: clonal in nearly all cases.
  • Bloods: FBC, blood-film for Sézary cells; flow cytometry.
  • Lymph-node USS / biopsy if palpable.
  • Staging CT chest / abdomen / pelvis ± PET-CT for haematological involvement.

Differentials

  • Classic mycosis fungoides — without granulomatous component.
  • Cutis laxa, anetoderma.
  • Granulomatous mycosis fungoides (variant without slack skin).
  • Sarcoidosis.
  • Lymphomatoid papulosis.
  • Cutaneous infections (mycobacterial, deep fungal) with granulomatous response.

Management

  • Treatment is similar to classic MF, tailored to disease stage:
    • Topical corticosteroids; nitrogen mustard / chlormethine gel where appropriate for MF-CTCL (NICE TA720).
    • Phototherapy: NBUVB, PUVA.
    • Radiotherapy: localised or total skin electron beam (TSEB).
    • Systemic: bexarotene, methotrexate, interferon-α, mogamulizumab.
  • Surgical excision of pendulous folds for symptomatic relief — high recurrence.
  • Long-term cancer surveillance for Hodgkin and other lymphomas; haematology / oncology MDT.

References

  1. LeBoit PE. Granulomatous slack skin. Dermatol Clin. 1994;12:375-389.
  2. Willemze R et al. The 2018 WHO-EORTC classification of cutaneous lymphomas. Blood. 2019;133:1703-1714.
  3. Alaibac M et al. Granulomatous slack skin: a rare variant of mycosis fungoides. J Am Acad Dermatol. 1996;34:1064-1066.
  4. Gilson D et al. British Association of Dermatologists and U.K. Cutaneous Lymphoma Group guidelines for the management of primary cutaneous lymphomas 2018. Br J Dermatol; 2019;180:496-526.

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