I’ve been reading Hugh McLean’s long and wonderful Nikolai Leskov: The Man and His Art (Cambridge, MA, 1977), and a leitmotif is that Leskov felt the need to avoid calling things novels.
First, in the early 1860s, Leskov “realized that in view of the widely held prejudice in favor of the big form he would have to write a novel if he hoped to earn a major reputation” (123). But his first novel, Некуда (No Way Out, 1864), was poorly received, and he never became a successful novelist (134). This was partly because he objected to the love plot that he considered obligatory in the novel, and never could get it right except perhaps in the story Леди Макбет Мценского уезда (“Lady Macbeth of the Mtsensk District,” 1865; see McLean 147).
When he began working on what eventually turned into Соборяне (Cathedral Folk, 1867-71), Leskov tried hard to avoid the term “novel”:
Leskov was determined to avoid the novel proper, which for him was indissolubly associated with Petersburg and with the angry, recent, “literary” side of his career. His Old Town would know nothing of that imported and artificial form, by very definition an invention, a fiction, which furthermore seemed to require the writer to take up the hackneyed subject of “romance.” Leskov undertook instead to write the history of Stary Gorod. […] As Thomas Eekman has observed, Cathedral Folk remains a novel in spite of Leskov’s denials, if that term is defined broadly enough to encompass any substantial work of fiction. Moreover, Leskov himself often slipped and referred to Cathedral Folk as a novel. Nevertheless, especially at the time he was writing it, Leskov insisted that his work belonged to a different genre. He sometimes called it “history” or a “history of bygone years,” but his final designation was khronika, “chronicle.” […] Initially, Leskov even put forward a compromise term, “novelistic chronicle” […] (174)
As McLean goes on to say and you can see for yourself here, Leskov got his publisher to advertise the forthcoming work as a “novelistic chronicle” (here it is under the earlier title Чающие движения воды and Leskov appears under his pseudonym Stebnitskii).
Later, discussing Детские годы (Years of Childhood, 1875), McLean adds this:
But Leskov, smarting from the failure of his own self-defined novels, tried to retaliate against the genre by adopting a narrow definition of it and then rebelling against the limits imposed by his own definition. (280)
I came to McLean’s book from a thoughtful critique of it by Irmhild Christina Sperrle in The Organic Worldview of Nikolai Leskov (Evanston, IL, 2002). She thinks McLean and others relied (of necessity) on biased accounts by Andrei Leskov (the author’s son) and Anatolii Faresov, and paint an inaccurate picture of a rather self-righteous and embittered Leskov (11-23).