CT Features of Lobular Capillary Hemangioma of the Nasal Cavity

Discussion

The term “pyogenic granuloma” is a misnomer because clear histologic and microbiologic features indicating an infectious origin are lacking. In addition, the term “granuloma” would allude to the presence of granulation tissue in the lesion, which is not typical of a lobular capillary hemangioma. Lobular capillary hemangioma and reactive granuloma are thought to be distinct entities. Nevertheless, lobular capillary hemangioma and reactive granuloma share several characteristics, including acute inflammation, an endothelial cell prominence, and an edematous and fibrous environment.^6,16 Although the differentiation can be challenging, reactive granuloma lacks the classic lobular growth pattern of the capillary proliferation that characterizes lobular capillary hemangioma. The histologic features of lobular capillary hemangioma are quite similar to those of rapidly involuting infantile hemangioma in that both lesions are composed of lobules of capillaries and surrounding fibrous tissue¹⁷ but are different from those of venous vascular malformation (also known as “cavernous hemangioma”), which are composed of dilated blood-filled spaces lined by flattened endothelium.

Puxeddu et al,⁴ in their clinical study comprising the largest number of patients with LCHNC to date, have identified previous nasal trauma and pregnancy as a possible cause in only 15% and 5% of patients with LCHNC, respectively. In a study comprising 128 children with lobular capillary hemangioma,¹⁶ 76.9% of lesions were found in the head and neck, and 76.7% had no history of trauma or predisposing factors. Congenital lobular capillary hemangioma in the oral mucosa also has been documented previously.¹⁸ Given these clinical and histologic features, lobular capillary hemangioma seems to be a benign neoplasm rather than a reactive process secondary to infection or trauma.⁶

The LCHNC lesion usually appears at endoscopy as a single red-to-purple, hypervascularized mass with a predilection for the anterior nasal fossa, particularly the anterior nasal septum. In our study, the LCHNC lesion arose from inferior turbinate in 5 (83.3%) patients and the nasal septum in 1 (16.7%) patient and predominantly involved the anterior, middle, and posterior portions of a nasal cavity in 2 (33.3%) patients each. The distribution of LCHNC in our study was quite different from that in the literature, including a clinical study comprising 40 patients with LCHNC.⁴ The difference in the distribution of LCHNC between our study and that in the literature may not attain clinical significance because of the small number of patients included in our study. Nevertheless, the inferior turbinate seems to be a common site of the origin of LCHNC. A few cases of LCHNC in pregnant women have been reported.^2,19,20 Some of the lesions have been known to regress after parturition.²¹ In our study, pregnancy was identified as a possible cause of LCHNC in 1 patient (16.7%). The LCHNC lesion did not regress spontaneously after delivery in this patient. Thus, she underwent endoscopic excision.

Imaging features of LCHNC have been reported in the literature as a part of clinical study or as single case reports (Table 2).^{1,3,4,13–15} Previously reported CT features of LCHNC can be summarized as a soft-tissue mass without bony destruction or invasion into the paranasal sinuses.^1,3,13 Histologically, the LCHNC lesion consists of 2 areas: a lobular and a superficial ulcerative area. The lobular area is characterized by capillary proliferation with a microscopically distinct lobular architecture. The superficial portion of the lesion may undergo secondary nonspecific changes, including stromal edema, capillary dilation, inflammation, and a granulation tissue reaction.^6,22

In our study, the findings of the LCHNC lesion on CECT consisted of an intensely enhancing mass and an iso- or hypoattenuating cap of variable thickness around the intensely enhancing mass in 5 (83.3%) of 6 patients. Of these, 3 (60.0%) cases showed linear and/or spotty enhancement within the cap. The LCHNC lesion in the remaining (16.7%) patient showed a hypoattenuating area containing linear or spotty enhancing foci, in addition to an intensely enhancing mass. We retrospectively speculated that the intensely enhancing mass corresponded histologically to a lobular area in all 6 patients; and the iso- or hypoattenuating cap of variable thickness in 3 patients and the hypoattenuating area in 1 patient, which contained linear and/or spotty enhancing foci, might correspond to the superficial ulcerative areas, respectively, though radiologic-histologic correlation has not been made in each case. The iso- or hypoattenuating cap of variable thickness that did not contain linear or spotty enhancing foci may be either a superficial ulcerative area or an inflammatory secretion, as in 2 patients in our study (patients 1 and 6). In 2 patients who underwent Gd-enhanced SE T1WI (TR/TE, 700/19 ms) (patient 1) and dynamic Gd-enhanced SE T1WI (TR/TE, 350/11 ms) at 1, 2, 3, and 4 minutes after intravenous administration of Gd (patient 5), the hypoattenuating cap and hypoattenuating area detected on CECT were intensely enhanced and gradually enhanced until 4-minute delayed imaging, respectively.

The discrepancy of findings between CECT and Gd-enhanced SE T1WI might be due to the relatively long scanning time of MR imaging, during which time, gradual fill-in of Gd in the hypoattenuating cap and area might occur. Accordingly, the hypoattenuating cap, which did not contain linear and/or spotty enhancing foci on CECT in 1 patient (patient 1), might correspond to a superficial ulcerative area rather than to an inflammatory secretion.

CT is superior to any other imaging modality in the evaluation of delicate bony architecture of the nasal cavities and paranasal sinuses. Cases with bony erosion rarely have been reported in the literature.⁴ Puxeddu et al⁴ reported a case of LCHNC involving the middle turbinate with erosion of the medial wall of the maxillary sinus. In our study, bony erosion (50.0%) and displacement (33.3%) were more common than those reported in the literature.^1,3,13 Bony erosion predominantly involved the site of the origin of the LCHNC lesion.

MR imaging findings of LCHNC have been sporadically reported in the literature.^4,14,23 Katori and Tsukuda¹⁴ reported a case of LCHNC that was isointense to muscle on T1WI and hyperintense with numerous small flow voids on T2WI. Puxeddu et al⁴ noted that the LCHNC lesion appeared as a soft-tissue mass with low SI on T1WI and high SI on T2WI and intense enhancement after intravenous administration of Gd. The MR imaging features of our patients (patients 1 and 5) were not significantly different from those in the literature (Table 2). The similarity of histologic features to rapidly involuting infantile hemangioma¹⁷ and high-velocity SI voids on FSE T2WI and Gd-enhanced SE T1WI in 2 patients in our study suggest that LCHNC is a high-flow lesion.

A differential diagnosis of a hypervascular mass of the nasal cavity in patients with nasal obstruction and/or epistaxis might include juvenile angiofibroma, angiomatous polyp, hemangioma, hemangiopericytoma, paraganglioma, angiosarcoma, and hypervascular metastases, particularly from kidney, thyroid, lung, or breast. None of these lesions have been reported to have an iso- or hypoattenuating cap of variable thickness around the intensely enhancing lobular mass in the literature. Accordingly, an intensely enhancing lobular mass and an iso- or hypoattenuating cap themselves are sufficient for suggesting the diagnosis of LCHNC, though a tailored prospective assessment with a large number of cases is anticipated.