Humpath.com - Human pathology

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• fibroepithelioma

  22 May

  Fibroepithelioma presents as a soft nodular lesion resembling a fibroma or papilloma, often on the lower part of the back.
  It is composed of thin anastomosing strands of basaloid cells set in a prominent loose stroma.
  The stroma has no elastic tissue.
  Merkel cells are quite prominent.
  It has been suggested, and subsequently disputed, that this variant derives its histological pattern from the spread of basal cell carcinoma down eccrine ducts, eventually replacing them with solid strands (...)

• basosquamous carcinoma

  22 May

  Basosquamous carcinoma is a controversial entity which can be defined as a basal cell carcinoma differentiating into a squamous cell carcinoma.
  It is composed of three types of cell:
  basaloid cells, which are slightly larger, paler and more rounded than the cells of a solid basal cell carcinoma;
  squamoid cells with copious eosinophilic cytoplasm;
  an intermediate cell which resembles that seen in metatypical tumors.
  Accordingly, the basosquamous carcinoma is sometimes confused with (...)

• metatypical basal cell carcinoma

  22 May

  Metatypical type
  Although the term ’metatypical’ is sometimes applied to tumors with mixed basaloid and squamous features, it should be reserved for the rare basal cell carcinoma composed of nests and strands of cells maturing into larger and paler cells.
  Peripheral palisading is often lost.
  The cells express much less keratin 17 and keratin 8 than do the cells in the more usual types of basal cell carcinoma.
  Peripheral palisading is less obvious than usual, and the stroma is often (...)

• infundibulocystic basal cell carcinoma

  22 May

  Infundibulocystic type
  The uncommon infundibulocystic variant, found most often on the face, is often confused with the keratotic type.
  It is small, well circumscribed, and composed of nests of cells arranged in an anastomosing fashion with little stroma.
  There are numerous small infundibular cyst‑like structures containing keratinous material and sometimes melanin.
  The stroma may contain amyloid and/or melanin.
  Multiple lesions are sometimes (...)

• sclerosing basal cell carcinoma

  22 May

  Sclerosing type
  The sclerosing category includes lesions which have also been referred to as fibrosing, scirrhous, desmoplastic and morpheic.
  The uncommon ’field fire’ type with central fibrosis resulting from regression should not be included in this category. Up to 5% of all basal cell carcinomas are of the sclerosing type.
  The tumor presents as an indurated, pale plaque with a slightly shiny surface and clinically indistinct margins. There are narrow elongated strands and small islands (...)

• adenoid basal cell carcinoma

  22 May

  Adenoid type
  The adenoid variant consists of thin strands of basaloid cells in a reticulate pattern. Stromal mucin is often quite prominent. The adenoid type is quite uncommon in a pure form. It may occur in association with the solid type.

• pigmented basal cell carcinoma

  22 May

  Pigmented type
  Melanin pigment is usually formed in solid, micronodular, multifocal superficial or follicular variants.
  Functional melanocytes are scattered through the tumor islands and there are numerous melanophages in the stroma. There are few melanosomes within the tumor cells.
  Melanosome complexes form in tumor cells as a consequence of repeated cycles of phagocytosis of melanosome‑containing tumor cells that have undergone apoptosis.
  Basal cell carcinomas of the usual type are (...)

• cystic basal cell carcinoma

  22 May

  Cystic type
  One or more cystic spaces are present toward the center of some or all of the tumor islands. This results from the degeneration of tumor cells centrally, and it may be associated with increased mucin between the tumor cells adjacent to the cyst.

• micronodular basal cell carcinoma

  22 May

  Micronodular type
  The micronodular variant resembles the solid type, but the nests are much smaller and the peripheral palisading is not always as well developed. The micronodular type has a much greater propensity for local recurrence than the solid type. Sometimes it infiltrates quite widely through the dermis and extends into the subcutis. The micronodular type is often included incorrectly with the infiltrating or solid (...)

• keratotic basal cell carcinoma

  22 May

  Keratotic type
  Keratotic type
  The keratotic variant is similar to the solid type, with nests and islands of basaloid cells with peripheral palisading.
  It differs in the presence of squamous differentiation and keratinization in the centers of the islands.
  There is usually very little stroma, and no lobular arrangement or follicular differentiation.

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