The Diagnostic Significance of Intracytoplasmic Lumina in Metastatic Neoplasms

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Abstract
The diagnostic significance of intracytoplasmic lumina (ICL) was evaluated in 61 consecutive and unselected metastatic neoplasms in lymph nodes, soft tissues, and bone [of humans] studied by light microscopy and EM. Their only common denominator was a light microscopic diagnosis of metastatic tumor of unknown primary site. Poorly differentiated squamous carcinomas, melanomas and lymphomas were also studied to see if they exhibited ICL. When ICL was present in all metastatic carcinoma of undetermined primary site, the breast is the most likely site of the primary tumor although the clinical context may modify the validity of this criterion. The demonstration of ICL in 2 adnexal carcinomas of sweat and meibomian glands should discourage pathologists from jumping to a conclusion of a metastatic breast carcinoma whenever ICL are found in a tumor in the skin. The presence of ICL seems to rule out the possibility of the neoplasm being a squamous carcinoma, a lymphoma, or a malignant melanoma. Histochemical techniques were useful in diagnosing cases of mesotheliomas and adenomatoid tumors in which ICL are positive with Alcian blue but become negative after hyaluronidase digestion. The notion that mucicarmine positivity might exclude breast carcinoma was not confirmed.