Oral fibrous histiocytoma‐associated calcification

To the Editor , We have read with great interest the article of Famenini and Cassarino1 on dermatofibroma-associated dystrophic calcification that was published in a recent issue of the Journal of Cutaneous Pathology. To our knowledge, no other well-documented cases of calcification associated with cutaneous or non-cutaneous dermatofibromas or fibrous histiocytomas were reported so far in the literature. However, we have some concerns and reservations regarding the case reported by Famenini and Cassarino. Recently, we had the opportunity to observe a case of oral fibrous histiocytoma (FH) with prominent calcifications. Even though fibrous histiocytomas are common cutaneous and non-cutaneous lesions, the phenomenon of dystrophic calcification is rare. The presence of intralesional calcifications in fibrous histiocytomas could be challenging for the pathologists and might expand the spectrum of differential diagnosis. A 12-year-old healthy male presented with an asymptomatic slowly growing intraoral nodule for two and a half months. Early, it was small and did not bother him. Later, the nodule became larger, projecting like a finger and caused discomfort when eating and brushing. Recently, the patient could not tolerate the lesion because it became painful and bleeding. His mother presented him to the oral and dental surgery unit in our institution for evaluation after seeking a medical advice and treatment with topical oral paste without improvement. Clinical examination revealed a rubbery to firm mobile pink to red polypoid growth with eroded surface and whitish covering. It involved the labial mandibular interdental gingiva of the lower anterior teeth between the right canine and right lateral incisor teeth. The remaining oral cavity and teeth were healthy. No regional lymphadenopathy was detected. Clinical differential diagnosis included fibroma, pyogenic granuloma and hemangioma. The nodule was surgically excised at its base via an intraoral approach under local anesthesia with primary closure. The excised nodule was fixed in formalin and submitted to the laboratory for pathologic evaluation. The patient did not recall a history of trauma. He had no history of vitamin D or calcium supplements intake. His complete blood count, inflammation serology markers, blood urea and electrolytes, creatinine, calcium and parathyroid hormone were within normal limits. This excluded a chronic systemic disease such as renal failure, hyperparathyroidism and hypercalcemia. No recurrence of the lesion was observed after 5 weeks follow up. The nodule measured 1.1× 0.9 cm. It was bisected and submitted for tissue processing. Microscopic examination showed a polypoid nodule involving the stroma of the gingival mucosa (Fig. 1A). The tip showed fibrinopurulent exudate and granulation tissue because of traumatic ulceration. The remaining intact squamous epithelium showed pseudoepitheliomatous hyperplasia. A characteristic low power feature of the nodule was the presence of fine granular deposits and clumps of dark basophilic calcified material. The nodule was composed of solid sheets of epithelioid to plump ovoid to spindle mononuclear cells interspersed by prominent vascular proliferation and wisps of collagen stroma (Fig. 1B,C). These cells had abundant cytoplasm with vesicular nuclei. Few mitotic figures were seen. Frequent multinucleated foreign body-type giant cells with on average 5–6 nuclei per cell were present. Scattered inflammatory cells composed