Lymphoplasmacytic Lymphoma Involving Marrow-Containing Submandibular Heterotopic Ossification: A Case Report and Literature Review.

BACKGROUND

Heterotopic ossification is characterized by the formation of mature bone within soft tissues and is most commonly associated with trauma, surgery, or chronic inflammation. The development of hematologic malignancies within heterotopic bone is exceedingly uncommon. We present a unique case of submandibular heterotopic ossification containing lymphoplasmacytic lymphoma and provide a review of calcified soft-tissue lesions encountered in the head and neck region.

CASE PRESENTATION: A 77-year-old man presented with a calcified nodule in the left submandibular region. Radiologic imaging demonstrated a well-circumscribed focus of soft-tissue ossification with no continuity to the mandible. The lesion was initially interpreted as a calcified lymph node, and watchful waiting was recommended. However, given the patient's reports of gradual enlargement and increasing discomfort during cervical rotation, surgical excision was performed. Histopathological examination revealed mature lamellar bone and marrow infiltrated by an atypical lymphoplasmacytic B-cell population. Immunohistochemical and PCR analysis demonstrated findings supportive of lymphoplasmacytic lymphoma, including IgM kappa light-chain restriction. Subsequent hematologic evaluation showed a serum IgM paraprotein and sparse bone marrow involvement.

CONCLUSION

To our knowledge, this represents the first documented case of lymphoplasmacytic lymphoma involving marrow-containing submandibular heterotopic ossification. As the lesion was the sole clinical manifestation of an otherwise occult lymphoproliferative disorder, this case underscores the importance of histopathological and molecular evaluation of excised calcified head and neck lesions, even when clinical and radiologic findings suggest a benign process.