Composed during the summer of 1887, the Piano quintet in A major Op. 81 (B 155) is one of Antonin Dvorak' s best-known and loved chamber works. Although it can often be found in concert programmes, has a considerable number of recorded versions and a recently updated critical edition, it has not been the subject of many analytical studies. An opportunity to consider its genesis is now provided by this article which includes the publication for the first time of a complete sketch presented by the composer to Turin-based ethnographer and composer Leone Sinigaglia in the early 1900s. This document makes it possible for us to broaden the horizons regarding its genesis based on a partial sketch preserved alongside the autograph score in the Czech Museum of Music in Prague. The length and complexity of the Turin sketch -- three bifolios with a total of twelve closely written pages full of musical examples and verbal comments -- require detailed examination. The article concentrates, in particular, on a highly significant page, the eighth, which offers the partial sketch of a Finale, discarded in the end by the composer, which is different from the final version. [ABSTRACT FROM AUTHOR]