Spongiotic hyperplasia of the oral mucosa: case series and immunohistochemical analysis.

The localized juvenile spongiotic gingival hyperplasia (LJSGH) mainly affects the maxillary vestibular attached gingiva of juvenile patients, without sex predilection. Similar lesions involving extragingival sites have not been reported to date. Here, we report 2 cases of extragingival soft tissue lesions with similar clinicopathological features to those reported in LJSGH and 12 cases of intraoral reactive soft tissue lesions microscopically showing LJSGH-like focal areas. The 2 cases were adult patients, affecting the maxillary alveolar ridge (55-year-old female) and hard palate (78-year-old male), which were diagnosed as "spongiotic hyperplasia of the oral mucosa." The 12 intraoral reactive soft tissue lesions (6 men and 6 women; mean age, 49.5 years) were diagnosed as inflammatory fibrous hyperplasia (n = 6), peripheral ossifying fibroma (n = 3), and pyogenic granuloma (n = 3), each of them presenting LJSGH-like focal areas. By immunohistochemistry, the spongiotic hyperplasia areas showed positivity for CK19, CK14, CK34βE12, and CAM5.2 (weak/focal), while CK4 was negative. Considering the anatomical locations (extragingival) of these 2 cases, the term "spongiotic hyperplasia of the oral mucosa" is suggested. Moreover, LJSGH-like focal areas can be detected when microscopically assessing common intraoral reactive soft tissue lesions.