Table 2 Intradermal mimics of uncertain biological behaviour
LesionClinical featuresHistologyImmunohistochemistry
Primitive non-neural granular cell tumourYoung to middle-aged adultsCells with prominent granular cytoplasm(+) Vimentin
Female predominanceNuclei with prominent eosinophilic nucleoli(+) CD10
Nuclear pleomorphism(+) PGP 9.5
Mild mitotic activity(+) NKI-C3
(+) CD 68
(−) S-100
(−) HMB-45
(−) CD34
(−) Desmin
(−) SMA
(−) Mart1/MelanA
Langerhans cell histiocytosis*Scaly, crusted papules or plaquesAggregates of Langerhans cells in the epidermis characterised by abundant blue–grey cytoplasm, indented oval nuclei with a central groove(+) S-100,
Affects children mainlyLittle or no cytological atypia(+) CD1a
Dermal infiltrate of Langerhans cells that form sheets with accentuation below the epidermis; absence of melanin pigment, and presence of eosinophils(+) Langerin (CD207)
(−) HMB-45
Mart 1/Melan A (−)
Inflammatory myofibroblastic tumour of the skinSolitary firm papules and nodulesBland spindle cells in dermis and subcutaneous fat(+) SMA, vimentin, CD68 in spindle cells
Heavy admixed inflammatory infiltrate(+) ALK-1
Hyalinised collagenous stroma(−) S-100, HMB-45, Mart1/MelanA, MiTF
  • *The ultrastructural hallmark of Langerhans cells is the rod-shaped or rocket-shaped granules (Birbeck granules, Langerhans cell granules), which may be needed to establish the diagnosis of Langerhans cell histiocytosis.

  • ALK-1, anaplastic lymphoma kinase-1; HMB, human melanoma black; MiTF, microphthalmia transcription factor; PGP, P glycoprotein; SMA, smooth muscle actin.