Case Study: Sudden Onset of a Painless, Soft Nodule in the Inguinal Region

Case at a Glance

A 30-year-old female presented with a painless, soft, mobile subcutaneous nodule in her inguinal (bikini line) area, which she noticed upon waking. Initial differential diagnoses included a lipoma, epidermoid cyst, and a non-inflamed ingrown hair follicle. A conservative 'watch and wait' approach was recommended.

Patient's Story

The patient, a 30-year-old female, presented with a chief complaint of a newly discovered lump on her left inguinal line. She stated it was not present the night before and seemed to have 'appeared over night.' The lump was entirely painless to the touch and she described its consistency as 'squishy.' Concerned, she attempted to squeeze the lesion with her fingernails, which produced no discharge and resulted in a minor surface scratch. Her medical history was significant only for the use of a progestin-only oral contraceptive. She is a non-smoker.

Initial Assessment

On physical examination, a solitary, well-demarcated, skin-colored subcutaneous nodule, approximately 1.5 cm in diameter, was noted in the left inguinal region. The nodule was soft, mobile, non-tender, and compressible. There were no overlying skin changes such as erythema, warmth, or a central punctum. A superficial linear abrasion was present on the surface, consistent with the patient's report of manipulation. No regional lymphadenopathy was palpated. The overall presentation was inconsistent with an acute abscess or infected cyst.

The Diagnostic Journey

The patient's acute presentation of a soft, painless, mobile nodule prompted several differential diagnoses. A lipoma, a benign tumor of adipose tissue, was considered a strong possibility due to the soft, 'squishy' consistency. An epidermoid cyst was also a consideration, although these typically feel firmer and may present with a characteristic central punctum. A sterile follicular cyst or a deep, non-inflamed ingrown hair (pseudofolliculitis) was also possible given the location, though these often present with some degree of tenderness or inflammation. Given the benign and asymptomatic nature of the lesion, an immediate invasive workup was deemed unnecessary. The initial recommendation was a period of watchful waiting.

Final Diagnosis

Clinical Diagnosis: Benign Lipoma.

Treatment Plan

The patient was advised to cease any further manipulation of the lesion to avoid irritation and potential secondary infection. She was instructed to monitor the nodule for any changes in size, shape, or for the development of symptoms such as pain, redness, or tenderness. A 'watch and wait' approach was implemented, with a recommendation to schedule an appointment with her primary care provider for in-person evaluation if the lesion persisted for more than two weeks, enlarged, or became symptomatic.

Outcome and Follow-up

The patient followed the advice and observed the lesion. Over the next few weeks, the nodule remained stable in size and asymptomatic. At a follow-up appointment one month later, her primary care provider confirmed the clinical impression of a small, subcutaneous lipoma. The patient was reassured of its benign nature and advised that no surgical excision was necessary unless it became cosmetically bothersome or symptomatic. The patient was satisfied with the outcome and required no further intervention.