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Pathology - Basal cell carcinoma
Definition: A collection of malignant epidermal tumors consisting of basaloid cells.
Epidemiology • Extremely prevalent neoplasms constituting 70% of all cutaneous cancers. • Primarily observed in fair-skinned people exhibiting sun damage.
Aetiology Cumulative exposure to ultraviolet (UV) radiation is the primary risk factor. Carcinogenesis • Nearly all exhibit mutations in genes that encode proteins associated with the sonic hedgehog pathway, predominantly PTCH1. A lesser percentage exhibit mutations in SMOOTHENED, which encodes the protein typically suppressed by the PATCHED1 protein.
Presentation: • Predominantly manifest as pearly papules or nodules in sun-exposed dermal regions. • Ulceration may transpire. Superficial variants manifest as erythematous patches that may be misidentified as eczematous lesions.
Histopathology: The tumor consists of clusters of tiny basaloid cells with little cytoplasm, exhibiting diverse growth patterns. The cells at the periphery of the clusters generally align in a palisade formation (peripheral palisading). The tumor stroma is generally loose and mucinous. Artefactual retraction gaps between tumor cells and stroma are frequently observed and may serve as a valuable diagnostic characteristic. A variety of morphological subtypes are identified, including nodular, superficial, infiltrative, morphoeic, and micronodular.
Prognosis: Exhibits locally invasive behavior; nonetheless, metastasis is exceedingly uncommon. Complete excision is typically curative. Recurrences are more prevalent at high-risk locations (head and neck) and with specific morphological subtypes (infiltrative, morphoeic, micronodular).
Pathological staging of skin carcinomas
Primary tumour (T)
pT1: tumour measures 2cm or less in size.
pT2: tumour measures > 2cm in size.
pT3: tumour invades muscle, bone, cartilage, jaws, and orbit.
pT4: tumour invades skull base, axial skeleton.
Regional lymph nodes (N)
pN1: single nodal metastasis measuring <3cm in size.< />pan>
pN2: single nodal metastasis measuring 3–6cm in size or multiple
nodal metastases, none measuring > 6cm.
pN3: any nodal metastasis measuring > 6cm
Definition: A collection of malignant epidermal tumors consisting of basaloid cells.
Epidemiology • Extremely prevalent neoplasms constituting 70% of all cutaneous cancers. • Primarily observed in fair-skinned people exhibiting sun damage.
Aetiology Cumulative exposure to ultraviolet (UV) radiation is the primary risk factor. Carcinogenesis • Nearly all exhibit mutations in genes that encode proteins associated with the sonic hedgehog pathway, predominantly PTCH1. A lesser percentage exhibit mutations in SMOOTHENED, which encodes the protein typically suppressed by the PATCHED1 protein.
Presentation: • Predominantly manifest as pearly papules or nodules in sun-exposed dermal regions. • Ulceration may transpire. Superficial variants manifest as erythematous patches that may be misidentified as eczematous lesions.
Histopathology: The tumor consists of clusters of tiny basaloid cells with little cytoplasm, exhibiting diverse growth patterns. The cells at the periphery of the clusters generally align in a palisade formation (peripheral palisading). The tumor stroma is generally loose and mucinous. Artefactual retraction gaps between tumor cells and stroma are frequently observed and may serve as a valuable diagnostic characteristic. A variety of morphological subtypes are identified, including nodular, superficial, infiltrative, morphoeic, and micronodular.
Prognosis: Exhibits locally invasive behavior; nonetheless, metastasis is exceedingly uncommon. Complete excision is typically curative. Recurrences are more prevalent at high-risk locations (head and neck) and with specific morphological subtypes (infiltrative, morphoeic, micronodular).
Pathological staging of skin carcinomas
Primary tumour (T)
pT1: tumour measures 2cm or less in size.
pT2: tumour measures > 2cm in size.
pT3: tumour invades muscle, bone, cartilage, jaws, and orbit.
pT4: tumour invades skull base, axial skeleton.
Regional lymph nodes (N)
pN1: single nodal metastasis measuring <3cm in size.< />pan>
pN2: single nodal metastasis measuring 3–6cm in size or multiple
nodal metastases, none measuring > 6cm.
pN3: any nodal metastasis measuring > 6cm
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