The corresponding process of peritoneum in the female is known as the canal of Nuck; and, when persistent, this also becomes distended with fluid and forms a cyst known as hydrocele of the canal of Nuck, occupying the inguinal canal.
In many of the lower animals the ovaries are contained within a serous sac derived from the peritoneum, which is so connected with the opening of the Fallopian tubes that when the ova escape from the ovary they enter these tubes and pass to the uterus without entering the general peritoneal cavity. This ovarian sac is subject to serous distention, and constitutes a condition called by Sutton an ovarian hydrocele. An homologous condition occurs sometimes in the human female, by pathological adhesion, and such cysts may attain large size. They project from, and are intimately connected with, the posterior layer of the broad ligament.
Hydroceles of the Neck.
—Hydroceles of the neck, so called, are cystic collections of congenital origin found in the cervical region, due to dilatation of ducts or clefts which should have disappeared at or before birth. The forms of cyst to which the name “hydrocele of the neck” are usually limited are recognizable at or soon after birth, and constitute fluctuating tumors, often extending beneath the clavicle into the axilla or down upon the thorax. They may occupy the entire lateral region of the neck, and may be unilateral or bilateral—may be single or multilocular, and may even intercommunicate.
They originate always beneath the deep fascia. Some of these cysts are undoubtedly due to dilatation of lymph spaces. This is particularly true of the multilocular forms. There is noted in many of them a tendency toward spontaneous recovery, but many again require operative measures for their eradication. Occasionally their walls are extremely vascular, even to the degree meriting the term nevoid.
Some of these cysts are considered by Sutton to be essentially examples of the laryngeal saccules which are met with as diverticula from the laryngeal mucous membrane, which undermine the deep cervical fasciæ of certain monkeys. These air chambers, which are normal in the monkey, communicate with the larynx through the thyrohyoid membrane, and occasionally run down beneath the upper border of the thorax. Many of the cysts having this resemblance are closely related to the hyoid bone and to the larynx, and there is much to substantiate the view thus quoted.
Glandular Cysts.
—Ranula is an altogether too comprehensive term which has long been used in surgery, alluding to cysts in the floor of the mouth, and not indicating minutely their character nor their exact location. At present this term should either be restricted in signification or be eliminated. If used, it should be confined to retention cysts due to obstruction of the submaxillary or sublingual ducts. Such obstruction is often caused by salivary calculi impacted in the duct orifices. In other instances it is due to cohesion of the margins of the outlet. A similar condition in the parotid duct is known, but is less common. Aside from this, certain other cysts originate from minute beginnings in and about the floor of the mouth, being due to dilatation of the mucous glands, particularly one near the tip of the tongue, sometimes known as Nuhn’s gland. Dermoid cysts in this locality are not uncommon. Formerly cysts of the floor of the mouth were described as ranula.
Pancreatic cysts correspond in large degree to salivary cysts, the pancreatic duct becoming dilated by retention when its orifice is obscured; and, indeed, the condition has been referred to as pancreatic ranula. Sometimes the canal is dilated in distinct portions, so that the condition resembles a string of cysts; at other times it is the terminal portion which is most enlarged. Such cysts attain large size and contain mainly mucoid material. Examples have been reported showing that they have attained a capacity of two gallons.
In the mesentery there sometimes develop cysts which are known as chyle cysts, whose sacs appear to be formed of separate mesenteric layers, their cavity being occupied by fluid identical with chyle. Such tumors also sometimes attain great size.