ISO-Oph-50 is a young low-mass object in the \sim 1 Myr old Ophiuchus star forming region undergoing dramatic changes in its optical/near/mid-infrared brightness by 2-4 mag .
We present new multi-band photometry and near-infrared spectra , combined with a synopsis of the existing literature data .
Based on the spectroscopy , the source is confirmed as a mid M dwarf , with evidence for ongoing accretion .
The near-infrared lightcurves show large-scale variations , with 2-4 mag amplitude in the bands IJHK , with the object generally being bluer when faint .
Near its brightest state , the object shows colour changes consistent with variable extinction of \Delta A _ { V } \sim 7 mag .
High-cadence monitoring at 3.6 \mu m reveals quasi-periodic variations with a typical timescale of 1-2 weeks .
The best explanation for these characteristics is a low-mass star seen through circumstellar matter , whose complex variability is caused by changing inhomogeneities in the inner parts of the disk .
When faint , the direct stellar emission is blocked ; the near-infrared radiation is dominated by scattered light .
When bright , the emission is consistent with a photosphere strongly reddened by circumstellar dust .
Based on the available constraints , the inhomogeneities have to be located at or beyond \sim 0.1 AU distance from the star .
If this scenario turns out to be correct , a major portion of the inner disk has to be clumpy , structured , and/or in turmoil .
In its observational characteristics , this object resembles other types of YSOs with variability caused in the inner disk .
Compared to other objects , however , ISO-Oph-50 is clearly an extreme case , given the large amplitude of the brightness and colour changes combined with the erratic behaviour .
ISO-Oph-50 has been near its brightest state since 2013 ; further monitoring is highly encouraged .