Ashtangasamgraha 37.4

37.4

viśeṣatastu tvaggate śalye vivarṇaḥ śopho bhavatyāyataḥ kaṭhinaśca |

māṃsagate śophābhivṛddhiḥ śalyamārgānupasaṃrohaḥ pīḍanāsahiṣṇutā coṣaḥ pākaśca ||

Specifically, when a foreign body is located in the skin, the swelling is discoloured, elongated, and hard.
When it is located in muscle, there is increase of swelling, non-healing of the tract of the foreign body, intolerance to pressure, burning heat, and suppuration.