Pezzo Capriccioso background

I just did a quick burst of 'net research and found this on Wikipedia:

Pyotr Ilyich Tchaikovsky composed his Pezzo capriccioso, Op. 62, for cello and orchestra in a single week in August 1887. Belying its title, this work is written in the somber key of B minor, the same key as the Symphony No. 6 Pathétique. The Pezzo is not capricious in a lighthearted sense. The capriccioso aspect comes from Tchaikovsky's fanciful treatment of various aspects of the work's simple theme. Despite some rapid passages and a turn to the major key, Tchaikovsky preserves the basic pulse and sober mood throughout the piece.

Tchaikovsky (right) with Anatoliy Brandukov, to whom he dedicated the Pezzo capriccioso.

The sobriety was a result of Tchaikovsky's sufferings with his friend Nikolay Kondratyev. Kondratyev was in the final throes of syphilis. After a brief remission, he had been taken to Aachen, Germany, where his family hoped the mineral waters there would prolong his life at least a few months. Instead, Kondratyev had taken a turn for the worse. Moreover, he proved a highly unpredictable, volatile and demanding patient, which unnerved the already death-shy Tchaikovsky. A visit to see friends in Paris—among them cellist Anatoliy Brandukov—proved only a brief respite.
All this suffering poured through the music Tchaikovsky was writing, as well.

From here: Pezzo Capriccioso