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Skin or subcutaneous lump

Specialties > Dermatology

Differential Diagnosis Schema 🧠

Benign Lesions

  • Lipoma: Soft, mobile, and non-tender subcutaneous nodules, usually slow-growing.
  • Epidermoid cyst: Contains keratin, often with a central punctum, commonly found on the face, neck, and trunk.
  • Dermatofibroma: Firm, hyperpigmented nodules, often with a dimple sign, typically on the lower legs.
  • Ganglion cyst: Soft or firm, non-tender lumps, often on the wrist or hand, arising from joint or tendon sheath.
  • Sebaceous cyst: Similar to epidermoid cysts but arise from sebaceous glands, often in hair-bearing areas.
  • Pilar cyst: Firm, mobile cysts typically on the scalp, filled with keratin.
  • Neurofibroma: Soft, skin-colored, or pigmented nodules, associated with neurofibromatosis.
  • Keloid: Raised, firm, fibrous growths following skin injury, more common in darker-skinned individuals.
  • Hemangioma: Red or purple vascular lesions, often present at birth and may regress spontaneously.
  • Molluscum contagiosum: Small, firm, umbilicated papules caused by poxvirus, commonly in children.
  • Dermoid cyst: Congenital lesions containing skin elements, often found near the eyes or along the midline.
  • Calcinosis cutis: Deposits of calcium in the skin, often hard and irregular, seen in conditions like scleroderma.
  • Lymphangioma: Benign malformations of the lymphatic system, often presenting as soft, fluid-filled cystic lesions.

Malignant Lesions

  • Basal cell carcinoma: Pearly, nodular lesions with rolled edges and possible ulceration, often on sun-exposed areas.
  • Squamous cell carcinoma: Scaly, crusted lesions or nodules, may arise from actinic keratoses, common on sun-exposed areas.
  • Melanoma: Irregularly pigmented lesions, asymmetrical with irregular borders, potentially arising from pre-existing moles.
  • Cutaneous lymphoma: Patches, plaques, or nodules, often pruritic and may resemble eczema or psoriasis initially.
  • Merkel cell carcinoma: Aggressive, rapidly growing nodules, typically on sun-exposed skin, with a red or violet color.
  • Kaposi’s sarcoma: Purplish, red, or brown plaques or nodules, often associated with HIV/AIDS.
  • Liposarcoma: Malignant tumors of fatty tissue, often presenting as deep, firm masses in the extremities or retroperitoneum.
  • Dermatofibrosarcoma protuberans: Slow-growing, firm nodules, often recur locally after excision.
  • Angiosarcoma: Rare, aggressive cancer of blood vessels, presenting as bruised, nodular, or ulcerated lesions.
  • Metastatic carcinoma: Secondary tumors, often presenting as firm nodules or plaques, typically on the trunk.
  • Synovial sarcoma: Malignant soft tissue tumor often near joints, presenting as a deep, firm, painless mass.
  • Neuroblastoma: In children, may present as firm, irregular, painless lumps, often abdominal.
  • Fibrosarcoma: Malignant tumor of fibrous tissue, presenting as a painless, slow-growing mass, often in the extremities.
  • Leiomyosarcoma: Malignant tumor of smooth muscle, presenting as a firm, painless mass, often in the uterus or retroperitoneum.
  • Dermatofibrosarcoma: Rare, slow-growing soft tissue sarcoma that may recur locally after excision.

Key Points in History 🥼

History of Presenting Complaint

  • Onset: Establish when the lump first appeared and whether it has changed in size or character.
  • Growth pattern: Assess whether the lump is growing rapidly, slowly, or has remained static.
  • Symptoms: Inquire about pain, tenderness, itching, or any discharge from the lump.
  • Trauma history: Ask if there was any preceding trauma or injury that could have contributed to the lump.
  • Previous lumps: Determine if the patient has had similar lumps before and their outcomes (e.g., resolution, removal, recurrence).
  • Systemic symptoms: Explore for systemic symptoms such as weight loss, fever, or night sweats that might suggest malignancy.
  • Occupation and hobbies: Consider any occupational or recreational activities that may expose the patient to repetitive trauma or irritants.
  • Sun exposure: Ask about sun exposure history, particularly for lumps on sun-exposed areas, to assess skin cancer risk.
  • Family history: Document any family history of skin cancer or other relevant conditions like neurofibromatosis.
  • Medical history: Review past medical history for conditions that predispose to skin or subcutaneous lumps (e.g., lipomas, neurofibromatosis).
  • Medication history: Consider medications that may contribute to the formation of lumps, such as corticosteroids or immunosuppressants.
  • Allergies: Ask about any history of allergic reactions or skin sensitivities.
  • Cosmetic concerns: Discuss any impact the lump has on the patient’s self-esteem or quality of life.
  • Travel history: Consider travel to regions where certain infectious or parasitic causes of lumps may be more common.
  • Previous interventions: Inquire about any previous biopsies, excisions, or treatments for the lump.
  • Impact on function: Assess if the lump interferes with daily activities or function, particularly if it is located near a joint or in a weight-bearing area.
  • Associated skin changes: Ask about any changes in the skin overlying the lump, such as ulceration, redness, or scaling.

Background

  • Medical history: Review chronic conditions such as diabetes, chronic infections, or autoimmune diseases that may predispose to lumps.
  • Medication history: Consider long-term medication use that may influence skin and subcutaneous tissue health.
  • Surgical history: Ask about any previous surgeries, particularly in the area of the lump.
  • Family history: Document any familial predisposition to conditions like lipomas, neurofibromatosis, or skin cancer.
  • Social history: Explore lifestyle factors such as smoking, alcohol use, and occupational exposures that may contribute to the formation of lumps.
  • Travel history: Consider exposure to endemic diseases that may cause skin or subcutaneous lumps.
  • Psychosocial factors: Assess the impact of the lump on the patient’s mental health, self-esteem, and social interactions.
  • Dietary habits: Evaluate the patient’s diet, particularly if there is a suspicion of nutritional deficiencies affecting skin and tissue health.
  • Occupational history: Investigate if the patient’s work involves exposure to physical or chemical hazards that could precipitate skin or subcutaneous lumps.
  • Sexual history: Consider sexually transmitted infections (STIs) that may present with lumps, particularly in the genital area.
  • Environmental exposures: Explore any contact with plants, animals, or chemicals that could contribute to lump formation.
  • Nutritional status: Poor nutrition can contribute to poor skin and tissue health and delayed healing of lumps.
  • Previous imaging or investigations: Review any prior investigations or imaging studies related to the lump.
  • Holistic assessment: Consider the patient’s overall health and well-being, including psychosocial factors.
  • Vaccination status: Particularly important in patients with possible infectious causes of lumps (e.g., HPV-related lesions).
  • Immunization status: Consider the impact of immune status on the development and persistence of skin or subcutaneous lumps.

Possible Investigations 🌡️

Initial Investigations

  • Ultrasound: First-line imaging to assess the nature (solid vs. cystic) and vascularity of the lump.
  • Fine needle aspiration (FNA): Minimally invasive technique to obtain cytology samples for diagnosis.
  • Core biopsy: More invasive than FNA, provides a larger tissue sample for histological examination.
  • Excisional biopsy: Complete removal of the lump for both diagnostic and therapeutic purposes, especially if malignancy is suspected.
  • MRI: Consider if the lump is deep-seated, or if malignancy or soft tissue involvement is suspected.
  • CT scan: Useful for assessing deeper structures, particularly in the abdomen or chest, or if bone involvement is suspected.
  • Blood tests: Full blood count, inflammatory markers (e.g., CRP, ESR), and liver function tests to assess for systemic involvement.
  • X-ray: Useful if the lump is near bone or to assess for calcification within the lump.
  • Dermatoscopy: Non-invasive examination of skin lesions to differentiate benign from malignant features.
  • Swab for microbiology: If infection is suspected, take a swab for bacterial, viral, or fungal culture.
  • Immunohistochemistry: To assess for specific markers, particularly in suspected malignancies.
  • Genetic testing: Consider if a genetic syndrome (e.g., neurofibromatosis) is suspected.
  • PET scan: Consider in cases of suspected metastatic disease.
  • Lymph node biopsy: If regional lymphadenopathy is present, particularly in suspected melanoma or squamous cell carcinoma.
  • Tissue culture: If an infectious etiology is suspected, particularly for chronic or non-healing lumps.
  • Serology: To assess for underlying infectious causes, particularly in the context of viral or systemic bacterial infections.
  • Photographic documentation: For monitoring changes in the lump over time, particularly for pre-malignant or early malignant lesions.
  • Autoimmune panel: If an autoimmune etiology is suspected (e.g., lupus, dermatomyositis).
  • HIV testing: Consider in patients with unexplained lumps and risk factors for HIV infection.
  • Referral to dermatology or oncology: For specialized assessment and management, particularly in complex or atypical cases.
  • Multidisciplinary team (MDT) discussion: In cases of suspected malignancy, involvement of an MDT for treatment planning is crucial.
  • Holistic assessment: Consideration of the patient’s overall health and well-being, including psychosocial factors.
  • Repeat biopsy: May be necessary if initial biopsy results are inconclusive or if the lump changes.

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Dermatology