AIMS: Very recent multidisciplinary investigations have allowed for the definition among lipomas of a clinical and histological subtype called spindle cell and/or pleomorphic lipoma, possibly associated with partial monosomy 16 and anomalies of chromosome 13. In order to get nearer to the underlying critical molecular changes further multidisciplinary pathological and genetic research is indicated, to identify which chromosome(s) anomalies are crucial in the development of these tumours. METHODS AND RESULTS: In an ongoing multidisciplinary study of lipomatous tumours, including clinical findings, morphology, histochemistry and cytogenetics, two instances were found of spindle cell lipoma with clonal chromosome changes. In both cases chromosome 13 was involved, whereas only one showed a partial monosomy 16. CONCLUSIONS: Partial monosomy 16 is a characteristic lesion in spindle cell lipoma, usually associated with anomalies of chromosome 13. The present report confirming a previous single observation indicates, however, that lesions of 13 may occur independently from lesions of 16, suggesting different underlying molecular lesions in these otherwise very similar lipomas.