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Adenoid cystic carcinoma of the lacrimal gland


Key points

  • Definition: Adenoid cystic carcinoma of the lacrimal gland (ACC LG) is a rare form of adenocarcinoma causing an extraconal, unencapsulated malignancy, usually arising from the lacrimal gland’s orbital lobe.

  • Synonym: cylindroma.

  • Classic clue: A middle aged woman presents with diplopia, proptosis, pain, and paresthesia. An unencapsulated, irregular, ovoid, soft tissue lacrimal fossa mass is evident resulting in inferiomedial globe displacement with a heterogeneous T2 signal.

Imaging

Computed tomography features

  • Computed tomography (CT) shows an unencapsulated, irregular, infiltrating, enhancing lacrimal gland mass (see Figure 42-1 , A and B ).

    FIGURE 42-1 ■, A, Axial contrasted computed tomography (CT) shows homogeneously enhancing soft tissue mass involving lateral aspect of left orbit causing exophthalmos. B, Coronal contrasted CT confirms clearly unencapsulated irregular soft tissue mass filling lacrimal gland fossa with no visualized separate lacrimal gland. Globe displaced inferiorly and medially. C, Axial T2 shows increased heterogeneous signal in lacrimal gland mass with irregular medial border. D, Axial T1 fat saturation with Gd shows moderately enhancing left lacrimal gland mass, causing exophthalmos and medial globe displacement. Note multinodular nonenhancing foci. E, Coronal T1WI demonstrates ovoid soft tissue mass in lacrimal gland fossa displacing orbital contents inferomedially. The signal is homogeneously hypointense to orbital fat and roughly isointense to EOMs. F, Coronal T2 shows increased heterogeneous signal in lacrimal gland mass containing multiple low signal internal foci. G, Coronal T1 fat saturation with Gd shows moderately enhancing lacrimal gland mass, causing inferomedial displacement of orbital structures. Note multifocal areas of poor enhancement.

  • Calcification is common (see Figure 42-2 , B and C ).

    FIGURE 42-2 ■, A, Axial nonenhanced computed tomography (NECT) shows right lacrimal gland mass with irregular outline causing exophthalmos and medial globe displacement. Basaloid type ACC. B, Axial NECT shows right LG mass with coarse Ca 21 adjacent to the lateral orbital wall. Basaloid type ACC LG. C, Coronal NECT shows irregular outlined right LG mass containing coarse calcifications near lateral orbital wall. Basaloid type ACC LG. D, Axial T2 shows increased heterogeneous signal in right LG mass with multiple nodular areas of decreased signal. Basaloid type ACC LG. E, Coronal T2 shows increased heterogeneous signal in right LG mass with multiple nodular areas of decreased signal. Basaloid type ACC LG. F, Axial T1 Gd shows heterogeneous enhancing right LG mass with multiple focal areas of decreased signal. Basaloid type ACC LG. G, Coronal T1 Gd shows heterogeneous enhancing right LG mass containing multiple focal areas of decreased signal. Basaloid type ACC LG.

  • Preoperative imaging suggests bony involvement of the lacrimal gland fossa in approximately 75% of cases.

  • 44% of those with ACC LG develop metastases.

Magnetic resonance imaging features

  • T1: On magnetic resonance imaging (MRI) the T1-weighted image is homogeneously hypointense to orbital fat (see Figure 42-1 , E ).

  • T2: On T2-weighted images show: • A mixed signal is present in 100% of some series (see Figures 42-1 , C and F, and 42-2 , D and E ).

    • Focal areas of hyperintensity may be seen (see Figure 42-1 , C ).

    • Sometimes a hypointense (basaloid type) image is seen (see Figure 42-2 ).

  • T1 Gd: With T1 Gd 35% of images show moderate enhancement with multifocal areas of poor enhancement (see Figure 42-1 , D ).

Clinical issues

Presentation

  • Most often present in 30- to 60-year-olds with diplopia, proptosis, and pain.

  • Pain is caused by bony or perineural spread.

Treatment

Surgery

  • Some say surgical excision should replace diagnostic incisional biopsy, followed by therapeutic excision.

  • Excision can be challenging particularly because of the propensity for the perineural tumor to spread.

  • Exenteration is routinely recommended by some, and by most when the tumor extends into or beyond the orbital apex.

Radiation therapy

  • Adjuvant or palliative radiotherapy is commonly given postoperatively (PO).

  • Some consider fast neutron therapy to be the most effective radiotherapy.

  • Brachytherapy with radioactive iodine (I 125 ) has been used.

Chemotherapy

  • Limited data are available on the efficacy of this modality.

  • Clinical trials continue to evaluate chemotherapy effectiveness.

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