Challenges in the diagnosis of cutaneous adnexal tumours

Abstract

The diagnosis of cutaneous adnexal neoplasms, a heterogeneous group of entities, is often perceived by practising pathologists as challenging. A systematic approach to diagnosis is necessary for classification of these lesions, which establishes the tumour differentiation (follicular, sebaceous, sweat gland or apocrine) and evaluates histological features differentiating between benign and malignant entities. Consideration of clinical history is a necessary adjunct in evaluation of the adnexal neoplasm, as characteristic anatomical sites are described for many adnexal lesions. In some instances, immunohistochemical studies may also be employed to aid the diagnosis. The differential diagnosis between primary cutaneous adnexal neoplasms and cutaneous metastases from visceral tumours may also be difficult. Clinical, radiological, histological and immunohistochemical characteristics will be further discussed, considering that the correct diagnosis has a significant impact on the patient's management and prognosis.

Histologic Mimics of Basal Cell Carcinoma

“…Adequate sampling to assess the depth of the lesion and the presence of perineural invasion are crucial because syringoma and DTE are superficial lesions that do not invade nerves. 85,86,89,90 Both MAC and mBCC are ill-defined and infiltrative lesions, although mBCC less frequently invades nerves and consists entirely of basaloid cells that have no ductal differentiation. 85,89,90 Conversely, peripheral palisading, tumor-to-stroma retraction, and myxoinflammatory stroma are rare in MAC.…”

“…85,86,89,90 Both MAC and mBCC are ill-defined and infiltrative lesions, although mBCC less frequently invades nerves and consists entirely of basaloid cells that have no ductal differentiation. 85,89,90 Conversely, peripheral palisading, tumor-to-stroma retraction, and myxoinflammatory stroma are rare in MAC. 85,89,90 Immunohistochemistry is generally not useful to discriminate between MAC and syringoma.…”

“…85,89,90 Conversely, peripheral palisading, tumor-to-stroma retraction, and myxoinflammatory stroma are rare in MAC. 85,89,90 Immunohistochemistry is generally not useful to discriminate between MAC and syringoma. 90 Staining with CEA and EMA highlight ductal structures in MAC, which may help differentiate it from DTE and mBCC.…”

“…85,89,90 Immunohistochemistry is generally not useful to discriminate between MAC and syringoma. 90 Staining with CEA and EMA highlight ductal structures in MAC, which may help differentiate it from DTE and mBCC. 86,90 In addition, CK15 stains positive in MAC and is negative in mBCC.…”

“…90 Staining with CEA and EMA highlight ductal structures in MAC, which may help differentiate it from DTE and mBCC. 86,90 In addition, CK15 stains positive in MAC and is negative in mBCC. 86,90 Reports are mixed regarding whether a subset of MACs may express Ber-Ep4, 53,91,92 and MACs may express p75NTR.…”