Subcutaneous node of the salivary gland (tuberculosis of salivary gland) is a rare infection of the salivary glands. In 1893, Depaoli first reported subcutaneous node of the salivary gland, and cases have been continuously reported since then.

bubble_chart Etiology

Subcutaneous node of the salivary gland can be either a primary or secondary infection. The route of infection is typically through lymphatic drainage from the skin of the head and face, the oropharynx, especially the tonsillar area, where subcutaneous node bacteria are present. Hematogenous infection, such as in cases of foxtail millet granulomatous subcutaneous node, cannot be entirely ruled out. Retrograde ductal infection is extremely rare. Kitamura reported a case of subcutaneous node in the parotid duct, possibly due to reduced salivary secretion and active subcutaneous node bacteria expelled from the lungs. However, Suzuki suggested that the patient also had a typical ileocecal subcutaneous node, making hematogenous infection a possibility as well. A few cases have a history of subcutaneous node or a family history of subcutaneous node.

bubble_chart Pathological Changes

The pathological process typically begins with an infection in the lymph nodes of the parotid gland, leading to subcutaneous node enlargement and rupture, which then affects the gland parenchyma. This results in characteristic subcutaneous node pathological changes, including nodules composed of epithelioid cells, lymphocytes, and Langhans giant cells, along with caseous necrosis.

bubble_chart Clinical Manifestations

It can occur at any age, but most commonly between 20 and 30 years old, accounting for 60–70%. There is no significant gender difference. The duration of the condition varies, ranging from as short as one month to as long as several years. It can occur in the parenchyma of the salivary glands or in the lymph nodes within the salivary glands. The latter is often misdiagnosed as a tumor and treated accordingly. Among the three major salivary glands, the most commonly affected is the parotid gland (lymph nodes) subcutaneous node. The primary infection appears in the parotid tissue, possibly originating from the tonsils or oral cavity. Typically, the parotid subcutaneous node is unilateral but may also involve both sides. Common locations include the area in front of the tragus and the pole of the parotid gland near the anterior border of the sternocleidomastoid muscle's mastoid attachment. Clinically, it presents as a painless mass that may feel firm or soft upon palpation, sometimes even fluctuant (due to caseous necrosis or suppurative infection). The mass is mobile and usually has well-defined borders. Pain may appear in the late stage [third stage]. Submandibular lymph subcutaneous nodes are very common and may sometimes involve the submandibular gland, leading to submandibular gland tissue subcutaneous nodes. Patients typically report a slowly growing mass, though occasionally there may be slight shrinkage during the gradual enlargement. Acute inflammation may also manifest as diffuse glandular tissue involvement, presenting with redness, swelling, and even fluctuance.

OT skin test, needle biopsy or inoculating the punctured material into guinea pigs can be valuable for diagnosis.

Parotid gland sialography, if the lesion is confined within the lymph nodes resembling a benign tumor, shows duct displacement and space-occupying sexually transmitted disease changes; if the lesion destroys the membrane and involves the gland parenchyma, duct interruption and iodized oil pooling resembling malignant tumor manifestations may be observed. Therefore, accurate preoperative diagnosis is very difficult. Definitive diagnosis can only rely on histopathological examination, and pus culture sometimes can also cultivate subcutaneous node bacilli.

bubble_chart Treatment Measures

Anti-subcutaneous node drug therapy. Abscess formation should be incised and drained. Since it is often misdiagnosed as a tumor, surgical resection is also one of the commonly used methods.