Basal Cell Carcinoma

Keratosis Pilaris Cure

Keratosis Pilaris Cure

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Synonym: Basal cell epithelioma.

Clinical Features:

■ Occurs in sites chronically exposed to the sun and increased in frequency from the third decade onward, although they have been reported in children and young adults.

■ Most frequently on the face and scalp, rarely arises on the digits, the back of the hand, dorsum of the foot, or on the ears.

■ Typically are solitary opalescent nodules with telangiectasia (Fig. 18A) or ulceration (Fig. 18B).

■ Common variant is the superficial type (Fig. 18C), which often appears as a thin plaque.

■ Morphea-form may present as hypopigmented, depressed firm plaque (Fig. 18D).

■ Other variants include cystic type, fibroepithelioma of Pinkus type, and pigmented basal cell carcinoma (Fig. 18E), which can mimic melanocytic nevi or melanomas.

■ Typically, basal cell carcinoma is locally aggressive, and may reach several centimeters in size, and if neglected may erode into muscle, bone, or brain. Basal cell carcinoma rarely metastasizes.

Microscopic Features:

■ Nodular type basal cell carcinoma is an expansile tumor within the papillary dermis or extending into the reticular dermis (Fig. 19A).

■ Composed of single or interconnected lobules of basaloid cells with scant cytoplasm.

Adjacent mucinous stroma that forms open clefts with the periphery of the nodules; the so-called "retraction artifact" (Fig. 19B).

Cells along the periphery of the nodules usually exhibit palisading cells with nuclear crowding (Fig. 19B). Tumors may exhibit central lobular cellular necrosis and, if extensive, as seen in breast carcinomas (Fig. 20A), gives rise to "comedo" carcinoma architecture. Tumors are often ulcerated with formation of crust. Superficial type basal cell carcinoma exhibits intermittent minute to large lobules of palisading basal cells extending downward from the base of the rete ridges or epidermis (Fig. 20C).

Mucinous stroma with retraction artifact subjacent to the atypical basaloid budding; however, retraction is not always seen, particularly in early lesions. Cystic basal cell carcinoma exhibits single or multiple large cystic cavities (Fig. 20B) within the central region of the tumor and contains degenerative cellular debris. Pigmented basal carcinoma exhibits pigment within tumor cells and an increase in melanocytes with numerous melanophages in the tumor stroma (Fig. 20D). Infiltrating type of basal cell carcinoma exhibits irregular thin strands of basaloid cells with deep extension among collagen bundles, nerve, vessels, muscle, adipocytes, or bone. Infiltrative type basal cell carcinoma may show more broad sheets superficially (Fig. 21A) and an infiltrative pattern deeply (Fig. 21B).

Infiltrative type basal cell carcinoma may show mild or marked fibrotic stroma and thus exhibits a spectrum in continuity with morphea-type basal cell carcinoma. Morphea-type or sclerosing basal cell carcinoma exhibits irregular thin branching strands of basaloid cells embedded in a dense fibrotic stroma (Fig. 22A). Perineural invasion (Fig. 20E) may be seen in any type of basal cell carcinoma but particularly with infiltrating and morphea types.

Tumors with marked intralobular mucin production may form anastomosing cords of basal cells embedded in the mucin, or form multiple small islands of mucin deposition.

Basal cell carcinomas may become a pseudoglandular or adenoid type (Fig. 23A) as mucin production within cords of basal cell carcinoma form pseudolumina. Basal cell carcinomas may exhibit appendageal differentiation such as eccrine or sebaceous differentiation (Fig. 23B).

Keratotic basal cell carcinoma exhibits squamous differentiation with horn pearl formation (Fig. 24A), whereas presence of squamous eddies or squamous differentiation (Fig. 24B) is often seen in squamatized basal cell carcinoma. Fibroepithelioma of Pinkus is a variant of basal cell carcinoma with thin strands of anastomosing basal cells separating a fibrous stroma (Fig. 25). Marked amyloid or colloid bodies may be seen in the surrounding stroma representing necrotic tumor cell aggregates or maybe seen within the tumor as well. Architectural and cellular overlap of superficial, nodular, infiltrating, and other types of basal cell carcinoma is more often the rule than the exception. Basal cell carcinoma is a common tumor; therefore, collision of lesions with other epidermal and dermal neoplasms produces unusual clinical appearance and includes basal cell carcinoma and seborrheic keratosis, intradermal melanocytic nevus, verruca vulgaris, syringoma, and melanoma.

Clinicopathologic Correlation:


Dome-shaped, nodule with pearly border and telangiectasia

Nodule of atypical basaloid cells with peripheral palisading and clefting

Nodulo-ulcerative: Same with ulceration

Same as above with overlying ulceration

Superficial erythematous patch/plaque: Can be confused with psoriasis or dermatitis

Usually multifocal atypical basaloid proliferation attached to the epidermis in the papillary dermis

Morphea-type: Sclerotic patch

Strands of atypical epithelium in dense fibrotic stroma


Mass presenting as cystic lesion

Cystic lesion with variable amount of atypical basaloid cells in the periphery

Fibroepithelioma of Pinkus : Polypoid mass

Polypoid with thin anastomosing strands of basaloid epithelium in mucinous fibrous stroma


May be confused with melanoma

Pigment in tumor cells as well as stroma

Differential Diagnosis:


Basal Cell Carcinoma

More organoid

Not organoid

Papillary mesenchymal bodies

No papillary mesenchymal bodies

No mucinous stroma

Mucinous stroma

No infiltration


No retraction artifact

Retraction artifact

Horn cysts

No horn cysts


1. Bhawan J. Ultrastructure of melanocyte-keratinocyte interactions in pigmented basal cell carcinoma. Pigment Cell Res 1979; 5:38-47.

2. Bhawan J, Mehregan A, Legg YJ, et al. Pigmented basal cell carcinoma and superficial spreading malignant melanoma: An unusual combination. J Cutan Pathol 1984; 11:471-475.

3. Shoji T, Lee J, Hong SH, et al. Multiple pigmented basal cell carcinomas. Am J Dermatopathol 1998; 20:199-202.

4. von Domarus HV, Stevens PJ. Metastatic basal cell carcinoma. Report of five cases and review of 170 cases in the literature. J Am Acad Dermatol 1984; 10:1043-1060.


Figures 13A, B and 15A, B have been reprinted with permission from the Dermatopathology Interactive Atlas

Dermatopathology Atlas

Figure 1 Clinical photograph showing scaly plaque with erythematous base (arrow) in preauricular area (A) and multiple (B) similar lesions on cheek and ear. Keratinocytic atypia involving the lower layers of the epidermis is seen (C).

Epidermal Cell

Figure 2 Keratinocytic atypia with disorderly arranged keratinocytes involve the lower two-thirds of the epidermis (A) while most of the epidermis appears atypical in (B). Note scattered dyskeratotic cells and supra-basal mitotic figure (arrow).

Atlas Cells Epidermis

Figure 3 Actinic keratosis with atypia confined to the basal layer on the left, lower-third in the middle and lower half on the right, all in one lesion (A). Also note solar elastosis in the dermis. Alternate parakeratosis overlying atypical squamous epithelium and orthokeratosis overlying eccrine duct (B) is a useful diagnostic clue. Also note sharp demarcation of basophilic acrosyringeal cytoplasm from eosinophilic cytoplasm of atypical keratinocytes. Acantholysis of the atypical squamous epithelium (C). This should not be confused with acantholytic blistering disorders.

Pubic Comparison

Figure 4 Atypia is confined to the downward budding of strands of squamous epithelium, while the bulk of the epidermis appears normal (A). Hyperplastic epidermis with atypia is seen in this hypertrophic variant of actinic keratosis (B). The atypical squamous epithelium is atrophic (C), microphotograph taken at 20x in comparison to hypertrophic type (B) taken at 4x. Also note the lichenoid lymphocytic infiltrate (C).

Clonal Bowens DiseasePsoriasis Pubic Region

Figure 5 Clinical photograph of Bowen's disease in non sun-exposed pubic area (A) and lower abdomen (B). These are sharply defined erythematous plaques with minimal scaling.

Squamous Cell Carcinoma Clear Cell Type

Figure 6 Transepidermal atypia of clear appearing keratinocytes in squamous cell carcinoma in situ (A). Note several dys-keratotic cells with large hyperchromatic nuclei and disorderly arrangement of keratinocytes (B) and scattered mitoses (C).

Keratotic Cells

Figure 7 Basal cell layer with eosinophilic cytoplasm while the suprabasal atypical cells appear clear—the eyeliner sign (A). Note the granular and upper spinous layers appear normal in B. Clonal nests (C) of and scattered (D) atypical keratinocytes are seen in clonal and pagetoid pattern respectively. Abundant melanin is seen in lower layers of the atypical keratinocytes (C) in the pigmented variant of squamous cell carcinoma in situ.

Keratinocyte CancersSquamous Cell Carcinoma DermatopathologySquamous Cell Carcinoma Situ

Figure 10 Moderately, well-differentiated squamous cell carcinoma (A, B) shows sheets of atypical squamous epithelium with intercellular bridges and occasional keratin pearl (arrowheads). Example of poorly differentiated squamous cell carcinoma (C). Note absence of keratinization or obvious evidence of squamous differentiation.

Squamous Cell Carcinoma Situ

Figure 11 In the absence of keratinization and intercellular bridges (A), demonstration of cytokeratins by immunostaining (B) is diagnostic of poorly differentiated squamous cell carcinoma. Marked pleomorphism with numerous mitoses and hyperchromatic nuclei (C) and marked variation in the nuclear size with multiple or giant nuclei (D) can be seen in some squamous cell carcinomas.

Pagetoid Basal Cell Carcinoma

Figure 12 Scattered individual atypical keratinocytes (A) can be seen within the epidermis exhibiting pagetoid pattern similar to Paget's disease and melanoma in situ. Acantholysis may be extensive (B) within the islands of atypical squamous epithelial cells. Spindle cell morphology in the spindle cell variant (C). Melanin pigment can be seen in atypical epithelial cells (D) of pigmented type squamous cell carcinoma.

Basal Cell Carcinoma Lower BodyBasal Cell Cancer The Penis

Figure 13 Verrucous carcinoma of the glans penis (A) and sole (B). Scanning photomicrograph showing mostly exophytic and minimally endophytic growth of squamous epithelium (C).

Keratin Pearls Squamous Cell CarcinomaBowen Disease Eyeliner Sign

Figure 15 Clinical photograph showing (A) solitary dome-shaped nodule with central keratotic center and (B) multiple lesions of keratoacanthoma. Scanning photomicrograph (C) correspond to the clinical features with central keratotic lesion and lips of normal epidermis adjacent to the downward proliferation of squamous epithelium.

Keratoacanthoma ErythematousBasal Cell Carcinoma Lip PhotosBasal Cell Epitheliomas

Figure 18 Clinical photographs of basal cell carcinoma: (A) nodular type with telangiectasia (arrow); (B) nodulo-ulcerative type; large (C), superficial erythematous plaque with ulceration in superficial type (D); sclerotic patch (arrow) on the nose in the morphea type; and (E) dark nodule (arrow) in the pigmented type.

Figure 18 Clinical photographs of basal cell carcinoma: (A) nodular type with telangiectasia (arrow); (B) nodulo-ulcerative type; large (C), superficial erythematous plaque with ulceration in superficial type (D); sclerotic patch (arrow) on the nose in the morphea type; and (E) dark nodule (arrow) in the pigmented type.

Types MorpheaSclerosing Eccrine Carcinoma

Figure 20 Photomicrographs of basal cell carcinoma showing central necrosis in the tumor islands resembling comedo pattern (A), large areas of tumor island with cystic degeneration (B), islands of atypical basaloid epithelium in superficial dermis attached to the epidermis (C), melanin in stroma as well as tumor cells (D), and perineural invasion (E).

Stromma Island

Figure 21 Irregular islands of atypical basaloid cells in minimally fibrotic stroma (A), extending deep into dermis (B), approaching the underlying skeletal muscle (arrow).

Morphea Type Basal Cell Carcinoma

Figure 22 Irregular thin strands of basaloid cells in fibrotic stroma characterize the morphea type of basal cell carcinoma.

Figure 21 Irregular islands of atypical basaloid cells in minimally fibrotic stroma (A), extending deep into dermis (B), approaching the underlying skeletal muscle (arrow).

Figure 22 Irregular thin strands of basaloid cells in fibrotic stroma characterize the morphea type of basal cell carcinoma.

Perivascukar And Intersitial DermatitisDermatopathology Cells

Figure 24 Keratin horn cysts (arrowheads) within the islands of basalold cells (A) In the keratotic variant of basal cell carcinoma. Note scattered multinucleated foreign body type of giant cells (arrows) caused by ruptured keratotic cysts, central squamous differentiation (arrowhead) within the islands of atypical basaloid cells in squamatized basal cell carcinoma (B). Note the island on the right shows only squamous differentiation reminiscent of squamous cell carcinoma (arrow).

Basaloid Squamous Cell CarcinomaFibroepithelioma Pinkus

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  • Jessica
    What is a pigmented variant of basal cell carcinoma?
    8 years ago
  • Steven McMillan
    What is infiltrative aggregates of basaloid cells?
    8 years ago
  • Eligio
    What does the structure of a keratinocytes cell look like?
    8 years ago
  • matthias
    Can a sclerosing Basal cell be caught early?
    7 years ago
  • miriam
    Can a dermatologist diagnose a sclerosing basal cell?
    7 years ago
  • christine
    What does chronic telogen effluvium look like?
    7 years ago
  • ethan mckay
    What is squamatized carcinoma?
    6 years ago
    What are squamatized keratinocytes?
    6 years ago
  • cordell taylor
    Is atypical basaloid neoplasm?
    4 years ago
  • Eija-Riitt
    What does psoriasis on the pubis look like?
    2 years ago
  • leonardo
    What is nodular basaloid neoplasm with peripheral palisading and clefting extends into the dermis?
    11 months ago

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