A Biopsy Diagnosis? Clinical Clues and Patterns to Help Distinguish Cutaneous Metastases: Part II of II*
*Part I of this review ran in the June 2011 issue.
Specific Cutaneous Metastases
Breast cancer is the primary cancer for 70 percent of cutaneous metastases in women overall, and cutaneous lesions usually occur on the anterior chest.3 There are several distinct clinicopathologic variants of cutaneous disease, including carcinoma erysipelatoides, en cuirasse, telangiectaticum, alopecia neoplastica and Paget's disease, which have been previously discussed (see "Presentation and Clinical Patterns"). In addition, cutaneous metastatic breast cancer may present as nodular metastatic carcinoma and carcinoma of the inframammary crease. The nodular form may be solitary, but usually presents as multiple smooth, firm lesions. Some nodules may ulcerate, and some may be pigmented and thus mimic melanoma. Carcinoma of the inframammary crease usually occurs in women with pendulous breasts and resembles intertriginous dermatitis.21
Lung cancer is the most common visceral tumor in men to metastasize to the skin and may be the first sign of an internal malignancy. Lung cancers can be classified into small cell and non-small cell carcinomas, which include squamous cell and adenocarcinoma.6 The latter two types each account for 30 percent of skin metastases from primary lung cancers, and undifferentiated tumors account for 40 percent.10 Squamous cell metastases are usually poorly differentiated with malignant cells arranged in a solid nesting pattern, and can be differentiated from primary squamous cell carcinoma of the skin by the absence of epidermal involvement.6,10 Adenocarcinoma metastases are moderately differentiated and have glandular features resembling primary lesions. Intracytoplasmic mucin can also be present.6,9 Undifferentiated tumors can histologically resemble lymphomas. They are usually derived from small cell lung carcinomas, which are anaplastic and contain cells with scant cytoplasm, hyperchromatic nuclei, dense core granules and clumped chromatin arranged in sheets, clusters or rosettes. This grouping of cells is less likely to occur in lymphoma, making small cell carcinoma the more likely diagnosis in undifferentiated tumors.6,10 Cutaneous lung metastases stain positive for thyroid transcription factor.
Esophagus. The frequency of cutaneous metastatis among patients with esophageal cancer varies in the literature, ranging from 1 percent (n=838 patients37) to 8.6 percent (n= 35 patients3). Metastatic lesions present as nodules that involve the head (especially scalp), neck and fingers.1,3 Squamous cell carcinoma, arising from the upper esophagus, is more common, but metastases from adenocarcioma do occur. Lesions are histologically similar to the primary lesions and stain positively for mucin.38