A T.J. Maxx store in Morton Grove, Ill. (Tim Boyle/Bloomberg)

It was hard to find any shred of upbeat news in the apparel industry last week, when heavyweights Macy’s, Kohl’s and Nordstrom all reported disappointing spring sales results.

But on Tuesday, the parent company of T.J. Maxx and Marshalls dropped a roaring first-quarter earnings report that showed no signs of the troubles engulfing its mid-price clothing counterparts. TJX Cos. saw revenue increase 10 percent to $7.5 billion, and recorded a 7 percent increase in comparable sales, or sales at stores open more than a year. The retailer even raised its earnings forecast for the year based on how strong business was in the first quarter.

The results continue a hot streak for a company that has for over a year managed to avoid the general malaise at the mall. And its success offers some insight about what is — and isn’t — proving enticing to customers in the current shopping environment.

The department store operator says shoppers have cut back on buying apparel, and foreign tourists have curbed spending. It cut its earnings outlook. (Reuters)

For starters, TJX’s strength is evidence that the recent woes of traditional retailers can not simply be chalked up to the rise of online shopping. Marshalls has no e-commerce offering at all, nor does HomeGoods, another fast-growing TJX-owned chain. T.J. Maxx’s online operation only launched in 2013 and represents just a tiny sliver of its business, one that it does not include in the tabulation of comparable sales. That means the robust growth seen across the company is coming entirely from old-fashioned, brick-and-mortar retailing.

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And it’s worth noting that in this quarter, like the last one, executives said the sales increase came not from selling pricier items, but rather came from a surge in foot traffic to its stores.

There’s no doubt that Amazon.com is starting to make serious headway in cracking the fashion category, and shoppers are getting more comfortable buying apparel in the online channel. But T.J. Maxx, Marshalls and HomeGoods offer hard-to-ignore evidence that customers are still plenty eager to shop in physical stores if the merchandise, price and service are on point.

The booming sales at TJX also underscore the extent to which shoppers generally are embracing off-price shopping, with its promise of name brands at low prices and a treasure hunt-like shopping experience. A rival off-price retailer, Ross Stores, has also been on a tear, delivering an 8 percent increase in revenue and a 4 percent increase in comparable sales last year.

Consumers’ enthusiasm for off-price shopping is shaking up the clothing industry in a variety of ways. For one, it has shaped the business strategies for upscale department stores Saks Fifth Avenue and Nordstrom.  These tony stores are increasingly reliant on their off-price outlets, Saks Off 5th and Nordstrom Rack, and they are putting more expansion muscle behind these concepts than they are their main department stores. At the beginning of 2014, there were 39 Saks Fifth Avenue stores in the United States and 72 Saks Off 5th stores. Today, there are 38 Saks department stores and 90 Saks Off 5th stores.

The mix of stores has been similarly changed at Nordstrom, which had 153 Rack stores two years ago and today has 200 of them. Meanwhile, the company has added only one full-price Nordstrom department store. It’s not hard to see why executives have chosen this path: While comparable sales were down 4.3 percent in the last quarter at Nordstrom, they were up a healthy 4.6 percent at Rack.

With off-price sales standing out as a rare bright spot in apparel retailing, it shouldn’t come as a surprise that several mega-retailers are looking to crash the off-price party: Macy’s debuted an off-price outlet last year it calls Macy’s Backstage. It is testing both standalone stores and shop-in-shop set-ups in existing Macy’s outposts. Executives say the early results are encouraging and that they eventually could roll out the shop-in-shop of version of Backstage to up to 300 of their locations.

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Kohl’s recently has opened two locations of Off/Aisle, its discount offering. And then there’s Find @ Lord & Taylor, an off-price concept that debuted last fall that aims to reach younger shoppers. Given these efforts by both existing off-price players and newcomers to the category, it appears the model is emerging as the medicine of choice to revive ailing department stores.

TJX executives seemed bullish on a Tuesday conference call with investors about their ability to beat back the new rivals, citing the company’s massive global team of 1,000 buyers as a competitive edge. Ernie Herrman, TJX’s chief executive, also seemed to passively suggest that department stores face challenges that TJX does not.

“We are only trying to do the off-price business, which I think creates another barrier to entry versus if we were a retailer trying to a do a few different types of business,” Herrman said.

And yet all the action might soon offer a test of just how voracious — and how durable — the appetite for off-price will be. In addition to the bumper crop of new concepts, TJX has big expansion plans for its chains. Currently, the company has 1,163 T.J. Maxx stores in the United States and 1,010 Marshalls stores. Executives say they believe there is a market for a combined 3,000 locations of these two chains, meaning they believe they have room to add more than 800 stores over the long haul. For some perspective, that means TJX’s planned slate of new stores alone is larger than the entire Macy’s fleet.

So far, TJX’s strategy is proving quite productive, with research firm eMarketer estimating that its stores generate about $309 in sales per square foot. But some may wonder how those economics might look different amid a dramatic expansion, as one location might start to cannibalize another’s business. And while TJX has done a remarkable job so far courting customers in the online era, the pressure from e-commerce is only going to grow.

It’s also worth noting in this moment of off-price fever that the model is hardly bulletproof. Loehmann’s, for example, shuttered its fleet in 2014 when it couldn’t keep up with its larger rivals such TJX and Ross. And Filene’s Basement re-launched as a web-only concept last fall after filing for bankruptcy and closing its physical locations only several years earlier. And then there are the online “flash sales” sites that aimed to bring off-price into a new era: Amazon said last month it was shutting down sales site MyHabit, while deals sites Gilt and Zulily were both acquired in the last year as their business models lost some of their luster with shoppers.

In other words, off-price models may be hot, but they are hardly a sure thing.

(Jeffrey P. Bezos, chief executive of Amazon, owns The Washington Post.)