Chronic hypobaric hypoxia induces a mild degree of pulmonary arterial hypertension with structural alterations in the peripheral portions of the pulmonary arterial tree of the native Andean highlanders. On the other hand, animals indigenous to high altitude do not show these changes and are adapted to hypobaric hypoxia. The small pulmonary arteries of seven native Himalayan highlanders were examined at autopsy and found to be thin-walled with no medial hypertrophy of the muscular pulmonary arteries or muscularization of the arterioles. These findings suggest that the Himalayan highlanders may be adapted to hypobaric hypoxia.

Differences in static and dynamic volumes may exist between high altitude residents of Indian Himalayas and their South American counterparts, as well as with acclimatized lowlander sojourners. Maximum expiratory flow-volume loops were recorded in healthy native highlanders of Ladakh (NH, N = 75) and in healthy acclimatized lowlanders (AL, N = 32) at an altitude of 3450 m in the western Indian Himalayas. The forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1), both corrected for a height of 168 cm, were significantly higher in NH [FVC: 5.02 (0.51) vs. 3.89 (0.45) L, p < 0.0001; FEV1: 4.27 (0.47) vs. 3.44 (0.37) L, p < 0.0001]. The flow rates at larger lung volumes (PEFR, FEF25, and FEF50) were similar in the two groups. The NH showed significantly higher flow rates at low lung volumes, that is, FEF75 and FEF75-85% [FEF75: 2.03 (0.69) vs. 1.70 (0.52) L/s, p = 0.0092; FEF75-85%: 1.42 (0.54) vs. 1.06 (0.35) L/s, p = 0.0001]. The exact mechanisms allowing the higher flow rates at low lung volumes remain to be elucidated, but it is possible that these findings may indicate an inherited adaptive response in the Ladakhi highlander.

Benign fibrous histiocytoma (BFH) is a benign fibrohistiocytic neoplasm. It is documented to occur in all anatomic sites with a strong predilection for sun exposed skin surfaces. Intra oral occurrence of BFH comprises a lesser percentage of cases with tongue being the least reported site. We report a case of BFH of the tongue with an emphasis on its histogenesis and a review of the literature.

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