I think this is pink disease (Erythricium salmonicolor) caused by a fungus that has a very broad host range and also infects mango.
You should see a characteristic pink/white or pink/orange appearance. A crust develops and it is "initially smooth, but cracks and becomes paler as it ages"
"Spores (conidia) are sometimes produced, on orange/red pustules scattered over the bark surface. "
"The fungus rarely causes death of mature trees, but can kill young trees."
The following is also from Plantwise which has a very good entry
"The wide host range of the pathogen makes local exclusion and eradication extremely difficult, as cross-infection can occur. Effective cultural control can be achieved by frequent pruning rounds and burning of infected debris providing the disease can be recognized in its earliest stages, but this is usually best combined with fungicide treatment. The pink encrustation and conidial pustules of the fungus remain viable for a considerable time after infected branches are detached from the tree.
Fungicides reported to show activity against E. salmonicolor include copper formulations (e.g. Bordeaux mixture, copper oxychloride, copper carbonate) (Ram et al., 1982; Kueh, 1986; Thankamma et al., 1986); tridemorph paints in an ammoniated latex base (Wastie, 1976; Edathil and Jacob, 1983); triadimefon granules (Villarraga, 1987); chlorothalonil paints in a latex/bitumen base (Anon, 1985); and fenpropimorph (in vitro) (Luz and Figueiredo, 1982). Pre- and post-monsoon application direct to trunk and branches with a specially designed spray lance was most efficient (Jacob and Idicula, 1999) in India. Application of a sulphur-lime slurry gave the most economic control in Kalimantan (Chee and Chiu, 1999). Of several fungicides tested for pink disease control of rubber in Vietnam, Validamycin A was the most effective (Duong et al., 1998)."
The cited references are not on the PlantWise page. We can search them later on for you if that is needed.
Another source says
"Control Strategies: Cut out affected branches some distance away from the advancing margins of the visible disease symptoms. Apply copper fungicides. Prune trees to open up the canopy to reduce humidity and render conditions less favourable for fungal infections."
The APS compendia say
"Pink disease is the most destructive stem disease of mango in the wet tropics. It affects twigs, branches, and trunks, and when it is severe, it reduces the fruit-bearing capacity of the trees. Trees that are 6-15 years old and have well-developed, dense canopies are most susceptible. In Malaysia, the disease is very common on inland soils in areas with high rainfall. It causes a reduction in leaf canopy , which creates large openings in the canopy through which sunlight can penetrate, scalding inner branches and causing the bark to crack."
Pink disease can be recognized by the appearance of silky white threads at the forks of branches or twigs . Under favorable, moist conditions, these mycelial threads coalesce to form a thin, rough, pink incrustation on the bark. This stage usually coincides with the penetration of the bark and wood by the fungus. Twigs or branches above these points may be killed, and the foliage becomes a shriveled, brown, dried-up mass . This is the advanced stage of the disease and may take several weeks or months to develop. The pink crust is often broken by irregular cracks, and a clammy, pinkish white layer may be formed over the pink crust (Plate 80). Also, orange pustules may be seen on the infected bark."
"The successful control of pink disease depends on early and
accurate identification of the disease symptoms followed by prompt application of a fungicide. The following fungicides have been found to control pink disease on mango and on other fruit crops; triadimefon, tridemorph, oxycarboxin, and flusilazol, and protectant fungicides such as copper hydroxide, copper oxide, copper oxychloride, and Bordeaux mixture. They are applied by spraying or by painting the infected bark with a brush.
Alternatively, infected branches can be removed, and exposed surfaces can be treated with a wound dressing. Wide tree spacing and canopies that allow free air circulation and sunlight penetration help reduce disease incidence."